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A small cube-shaped spacecraft with long wing-like solar panels is shown flying towards a relatively large asteroid with an even bigger asteroid nearby.

Find out more about the historic first test, which could be used to defend our planet if a hazardous asteroid were discovered. Plus, explore lessons to bring the science and engineering of the mission into the classroom.


In an attempt to alter the orbit of an asteroid for the first time in history, NASA will crash a spacecraft into the asteroid Dimorphos on September 26. The mission, known as the Double Asteroid Redirection Test, or DART, will take place at an asteroid that poses no threat to our planet. Rather, it's an ideal target for NASA to test an important element of its planetary defense plan.

Read further to learn about DART, how it will work, and how the science and engineering behind the mission can be used to teach a variety of STEM topics.

Why It's Important

The vast majority of asteroids and comets are not dangerous, and never will be. Asteroids and comets are considered potentially hazardous objects, or PHOs, if they are 100-165 feet (30-50 meters) in diameter or larger and their orbit around the Sun comes within five million miles (eight million kilometers) of Earth’s orbit. NASA's planetary defense strategy involves detecting and tracking these objects using telescopes on the ground and in space. In fact, NASA’s Center for Near Earth Object Studies, or CNEOS, monitors all known near-Earth objects to assess any impact risk they may pose. Any relatively close approach is reported on the Asteroid Watch dashboard.

Six triangular sections fan out from a shadowed view of Earth describing the PDCO's various activities, including 'Search, Detect & Track', 'Characterize', 'Plan and Coordinate', 'Mitigate', and 'Assess'.

NASA's Planetary Defense Coordination Office runs a variety of programs and initiatives aimed at detecting and responding to threats from potentially hazardous objects, should one be discovered. The DART mission is one component and the first mission being flown by the team. Image credit: NASA | + Expand image

While there are no known objects currently posing a threat to Earth, scientists continue scanning the skies for unknown asteroids. NASA is actively researching and planning for ways to prevent or reduce the effects of a potential impact, should one be discovered. The DART mission is the first test of such a plan – in this case, whether it's possible to divert an asteroid from its predicted course by slamming into it with a spacecraft.

Eyes on Asteroids is a real-time visualization of every known asteroid or comet that is classified as a near-Earth object, or NEO. Asteroids are represented as blue dots and comets as shown as white dots. Use your mouse to explore the interactive further and learn more about the objects and how we track them. Credit: NASA/JPL-Caltech | Explore the full interactive

With the knowledge gained from this demonstration, similar techniques could be used to deflect an asteroid or comet away from Earth if it were deemed hazardous to the planet.

How It Works

With a diameter of about 525 feet (160 meters) – the length of 1.5 football fields – Dimorphos is the smaller of two asteroids in a double-asteroid system. Dimorphos orbits the larger asteroid called Didymos (Greek for "twin"), every 11 hours and 55 minutes.

Various Earth objects are shown to scale ranging from a bus at 14 meters to the Burj Khalifa skyscraper at 830 meters. Dimorphos at 163 meters is shown between the Statue of Liberty (93 meters) on its left and the Great Pyramid of Giza (139 meters) on its right. Didymos is shown between the One World Trade Center (546 meters) on its left and the Burj Khalifa on its right.

The sizes of the two asteroids in the Didymos system relative to objects on Earth. Image credit: NASA/Johns Hopkins APL | + Expand image

Neither asteroid poses a threat to our planet, which is one reason why this asteroid system is the ideal place to test asteroid redirection techniques. At the time of DART's impact, the asteroid pair will be 6.8 million miles (11 million kilometers) away from Earth as they travel on their orbit around the Sun. Regardless of how much or how little the orbit of Dimorphos is changed by DART, the asteroid will not become a threat to Earth.

The DART spacecraft is designed to collide head-on with Dimorphos to alter its orbit, shortening the time it takes the small asteroid to travel around Didymos. Compared with Dimorphos, which has a mass of about 11 billion pounds (five billion kilograms), the DART spacecraft is light. It will weigh just 1,210 pounds (550 kilograms) at the time of impact. So how can such a light spacecraft affect the orbit of a relatively massive asteroid?

You can use your mouse to explore this interactive view of DART's impact with Dimorphos from NASA's Eyes on the Solar System. Credit: NASA/JPL-Caltech | Explore the full interactive

DART is what’s known as a kinetic impactor because it will transfer its momentum and kinetic energy to Dimorphos upon impact, altering the asteroid's orbit in return. Scientists can make predictions about some of these effects thanks to principles described in Newton's laws of motion.

Newton’s first law tells us that the asteroid’s orbit will remain unchanged until something acts upon it. Using the formula for linear momentum (p = m * v), we can calculate that the spacecraft, which at the time of impact will be traveling at 3.8 miles (6.1 kilometers) per second, will have about 0.5% of the asteroid’s momentum. The momentum of the spacecraft may seem small in comparison, but it's enough to make a detectable change in the speed of Dimorphos' orbit.

But there is more to consider in testing whether the technique could be used in the future for planetary defense. For example, the formula for kinetic energy (KE = 0.5 * m * v2) tells us that a fast moving spacecraft possesses a lot of energy.

When DART hits the surface of the asteroid, its kinetic energy will be 10 billion joules! A crater will be formed and material known as ejecta will be blasted out as a result of the impact. In this case, asteroid material equalling 10-100 times the mass of the spacecraft itself will be ejected out of the crater. The force needed to push this material out will be matched by an equal reaction force pushing on the asteroid in the opposite direction, as described by Newton’s third law.

This animation shows conceptually how DART's impact is predicted to change Dimorphos' orbit from a larger orbit to a slightly smaller one that's several minutes shorter than the original. Credit: NASA/Johns Hopkins APL/Jon Emmerich | Watch on YouTube

How much material will be ejected, and its recoil momentum, is still unknown. A lot depends on the surface composition of the asteroid. Laboratory tests on Earth suggest that if the surface material is poorly conglomerated, or loosely formed, more material will be blasted out. A surface that is well conglomerated, or densely compacted, will eject less material. As a result, the impact will also tell us more about the composition of Dimorphos.

After the DART impact, scientists will use a technique called the transit method to see how much the impact changed Dimorphous' orbit. As observed from Earth, the Didymos pair is what’s known as an eclipsing binary, meaning Dimorphos passes in front of and behind Didymos from our view, creating what appears from Earth to be a subtle dip in the combined brightness of the pair. Scientists can use ground-based telescopes to measure this change in brightness and calculate how quickly Dimorphos orbits Didymos.

A large cylindrical building with faceted sides has an opening at the top where two parts of a dome appear to be pulled apart allowing the telescope to view the darkened night sky.

The Lowell Discovery Telescope at Lowell Observatory in Arizona is one of the telescopes across the globe that will be used to evaluate the result of the DART impact. Image credit: Lowell Observatory | + Expand image

One of the biggest challenges of the DART mission is navigating a small spacecraft to a head-on collision with a small asteroid millions of miles away. To solve that problem, the spacecraft is equipped with a single instrument, the DRACO camera, which works together with an autonomous navigation system called SMART Nav to guide the spacecraft without direct control from engineers on Earth. About four hours before impact, images captured by the camera will be sent to the spacecraft's navigation system, allowing it to identify which of the two asteroids is Dimorphos and independently navigate to the target.

Two white points of light are circled in a fuzzy field of stars. The slightly larger point of light near the far right of the image is labeled Didymos.

A composite of 243 images of Didymos and Dimorphos taken by the DART spacecraft's DRACO camera on July 27, 2022, as the spacecraft was navigating to its target. Image credit: JPL DART Navigation Team | + Expand image | › DART image gallery

DART is not just an experimental asteroid impactor. The mission is also using cutting-edge technology never before flown on a planetary spacecraft and testing new technologies designed to improve how we power and communicate with spacecraft.

Learn more about the engineering behind the DART mission, including the innovative Roll Out Solar Array and NEXT-C ion propulsion system, in this video featuring experts from the mission. Credit: APL | Watch on YouTube

One such technology that was first tested on the International Space Station and is being used on the solar-powered DART spacecraft, is the Roll Out Solar Array, or ROSA, power system. As its name suggests, the power system consists of flexible solar panel material that is rolled up for launch and unrolled in space.

The Roll Out Solar Array, shown in this animated image captured during a test on the International Space Station, is making its first planetary journey on DART. Image credit: NASA | + Expand image

Some of the power generated by the solar array is used for another innovative technology, the spacecraft's NEXT-C ion propulsion system. Rather than using traditional chemical propulsion, DART is propelled by charged particles of xenon pushed from its engine. Ion propulsion has been used on other missions to asteroids and comets including Dawn and Deep Space 1, but NEXT-C's ion thrusters have higher performance and efficiency.

Follow Along

There are a number of ways to follow along with this exciting event and all the science from the mission.

On September 26, watch NASA Live from 3 to 4:30 p.m. PDT (6 to 7:30 p.m. EDT) to hear commentary from experts before and during the impact at Dimorphos. Images from DART, which will impact the asteroid at 4:14 p.m. PDT (7:14 p.m. EDT), will be streamed to Earth in real-time and shown during the broadcast.

Watch here from 3 to 4:30 p.m. PDT (6 to 7:30 p.m. EDT) on Monday, Sept. 26 to hear live commentary from experts before and after the impact at Dimorphos. | Watch on YouTube

In the days following the event, NASA expects to receive images of the impact from a cubesat that will be deployed by DART before impact. The cubesat, LICIACube, which was provided by the Italian Space Agency, is designed to capture images of the impact, the ejecta cloud, and perhaps even the impact crater left behind by DART. The James Webb Space Telescope, the Hubble Space Telescope, and the Lucy spacecraft will observe Didymos to monitor how soon reflected sunlight from the ejecta plume can be seen. In the following weeks, DART team members will continue observing the asteroid system to measure the change in Dimorphos’ orbit and determine what happened on its surface. In 2024, the European Space Agency plans to launch the Hera spacecraft to conduct an in-depth post-impact study of the Didymos system.

Learn more about DART and see the latest images and updates on the mission website. Plus, explore even more resources on this handy page.

Teach It

The mission is a great opportunity to engage students in the real world applications of STEM topics. Students can even observe the results of their engineering design challenges at the same time as the results of the mission are streamed back to Earth! Start exploring these lessons and resources to get students engaging in STEM along with the mission.

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TAGS: Asteroids and Comets, DART, near-Earth objects, planetary defense, Science, K-12 Education, Teachers, Educators, Parents, Teachable Moments

  • Lyle Tavernier
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Collage of James Webb Space Telescope's first images featured in this article.

Here's what we learned from the first set of images captured by NASA's newest space observatory and how to translate it into learning opportunities for students.


NASA’s newest space observatory, the James Webb Space Telescope, has returned its first set of images and spectra of five different targets – from nebulae to exoplanets to galaxy clusters – revealing the universe in ways never before seen. These targets, selected by a team of experts, represent just the start of the telescope's science operations and the beginning of our ability to see the universe in a whole new way.

Read on to learn more about what the space-based observatory’s images can tell us about the cosmos, how they were captured, and how to engage learners in the science and engineering behind the mission.

What JWST Saw

New Details Revealed About the Birth of Stars

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What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth. Credit: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

Stellar nurseries, young stars, and protostellar jets, which are narrow, ultra-fast streams of gas emanating from baby stars, are all on display in this image of the Carina Nebula, a cloud of gas and dust approximately 7,600 light years away.

Nebulae are massive clouds of gas and dust, some spanning up to hundreds of light-years across. Thanks to its infrared cameras, JWST can peer into these dusty regions of space, revealing incredible details previously unseen by other telescopes.

Within the Carina Nebula, a star-forming region known as NGC 3324 was captured by the Webb telescope in this image. As the edge of this region moves inward toward the gas and dust, it may encounter unstable areas. The pressure changes can cause the gas and dust to collapse, forming a new star in a process called accretion. However, if too much material is pushed away, it may prevent a star from forming.

The Webb telescope’s observations in nebulae like this will help scientists answer some of the unknown questions of astrophysics, like what determines the number of stars in a certain region and why do stars form with certain masses.

Scientists can also learn how star formation affects these clouds. Little is known about the numerous small, or low-mass, stars within nebulae. But by studying the jets revealed in the new image, scientists can understand how these stars are expelling gas and dust out of the cloud, thereby reducing the amount of material available to form new stars. Furthermore, scientists will be able to get a full count of these low-mass stars and account for their impact throughout the nebula.

Signs of Water on a Distant Planet

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A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

JWST's observations of exoplanet WASP-96 b, a planet outside our solar system, is not an image but a spectrum of light. Within the spectrum are highlights that indicate the presence of water molecules. The spectrum also shows evidence of clouds and haze, which were thought not to exist in WASP-96 b's atmosphere.

WASP-96 b is an exoplanet made up mostly of gas. About half the mass of Jupiter, but slightly larger, it orbits much closer to its star, completing a revolution every 3.4 days compared with 12 years for Jupiter.

This measurement, known as a transmission spectrum, was collected as WASP-96 b transited, or passed in front of, its host star from the perspective of the telescope. It compares the light that passed through the atmosphere of the exoplanet with the light from the planet's parent star alone. As a result, it is possible to see the amount of light at each wavelength blocked by the planet and absorbed by its atmosphere, telling scientists the size of the planet and the chemicals contained in its atmosphere.

While WASP-96 b’s spectrum had been captured before, the Webb telescope provided the most detailed view of its spectrum in near-infrared, and the improved resolution completely changed our understanding of the exoplanet’s atmosphere. Using this spectrum, scientists will be able to measure the amount of water in the exoplanet's atmosphere, determine how much oxygen and carbon it contains, infer the make-up of the planet, and even how, when, and where it formed.

Star Pair Coming Into Focus

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NASA’s Webb Telescope has revealed the cloak of dust around the second star, shown at left in red, at the center of the Southern Ring Nebula for the first time. It is a hot, dense white dwarf star. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

Two distinct stars can be seen in this image of the center of the Southern Ring Nebula – a pairing that was believed to exist but was not visible in previous images.

The star pair came into view thanks to the space telescope's MIRI instrument, which is designed to capture wavelengths of light in the mid-infrared range of the electromagnetic spectrum. MIRI’s ability to see in the mid-infrared revealed that the older of the two stars is surrounded by dust. Seeing this dust clearly is what makes the second star visible in the image. While the brighter star is in an earlier stage of its life, it will likely form its own planetary nebula in the future.

About 2,500 light-years away from Earth, the Southern Ring is a planetary nebula – a shell of gas and dust shed from a dying white dwarf star at its center. Its gases stretch out for nearly half a light-year and are speeding away from the star at approximately nine miles per second!

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The bright star at the center of NGC 3132, while prominent when viewed by NASA’s Webb Telescope in near-infrared light, plays a supporting role in sculpting the surrounding nebula. A second star, barely visible at lower left along one of the bright star’s diffraction spikes, is the nebula’s source. It has ejected at least eight layers of gas and dust over thousands of years. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The images from JWST reveal that starlight streams out of the nebula in fine lines, the result of holes in the surrounding gas and dust cloud. The types and locations of different molecules within the cloud, gleaned from the captured spectra, will help to fine tune our understanding of the structure, composition, and history of this nebula, and with future observations, other nebulae.

How Galaxies Interact

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An enormous mosaic of Stephan’s Quintet is the largest image to date from NASA’s James Webb Space Telescope, covering about one-fifth of the Moon’s diameter. It contains over 150 million pixels and is constructed from almost 1,000 separate image files. The visual grouping of five galaxies was captured by Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The Webb telescope's capabilities bring new eyes to a cluster of galaxies first discovered in 1877 and known as Stephan’s Quintet. On display in this sharp new image are regions of new star birth containing millions of young stars as well as tails of gas, dust, and stars being ripped from galaxies as a result of gravitational forces between the galaxies.

Stephan’s Quintet is a dense cluster of galaxies located 290 million light-years away in the constellation Pegasus. Four of the five galaxies within the quintet are locked in orbits that repeatedly bring them close to one another. The fifth (leftmost) galaxy is seven times closer to Earth than the others. But its location within the line of sight of the distant four makes it appear to be grouped with them. What looks like speckles surrounding the nearby galaxy and could be mistaken for digital noise is actually individual stars from that galaxy.

It may seem distant in pure numbers, but Stephan's Quintet is relatively close compared to galaxies that are billions of light-years away. Its proximity gives astronomers a great view of the interactions that occur between galaxies that are near to each other.

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The MIRI instrument measured the composition of gas around the black hole at the center of one of the galaxies in Stephan's Quintent to find a region filled with hot, ionized gases, including iron, argon, neon, sulfur and oxygen (top spectrum). The instrument also revealed that the supermassive black hole has a reservoir of colder, denser gas with large quantities of molecular hydrogen and silicate dust (bottom spectrum). Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The detail exposed will allow scientists to understand the interactions occurring in much more distant – and harder to observe – galaxies. Close inspections of galactic nuclei captured in mid-infrared by the telescope's MIRI instrument revealed hot gas being stripped of its electrons by winds and radiation from a supermassive black hole at the center of one galaxy. The new detail helped scientists determine that iron, argon, neon, sulfur and oxygen, as well as silicate dust are contained in these gases.

Meanwhile, the telescope's NIRSpec instrument – which can capture up to 100 spectra at a time – was able to identify atomic and molecular hydrogen as well as iron ions in the gases around the black hole. These observations will provide a greater understanding about the rate at which supermassive black holes feed and grow.

Thousands of Galaxies in a Grain of Sand

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NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

This image contains thousands of galaxies as well as the faintest objects yet observed in the infrared. Known as a deep field image, it was made by pointing the telescope at the target for an extended period of time, allowing the detectors to collect as much of the faint, distant light as possible. JWST captured this deep field image in just 12.5 hours, while the Hubble Space Telescope spent two weeks capturing its deepest images. (Note that Hubble also observed this galaxy cluster, but not as a deep field image.)

Hold a single grain of sand at arm's length and you could cover the entire area of space captured by this image. Keen observers will notice what appear as warped or stretched galaxies. Those are the result of gravitational lensing, a phenomenon in which the gravity of the galaxy cluster centered in the foreground bends the light from background galaxies magnifying and distorting their light. Taking advantage of this phenomenon allows for viewing of extremely distant and very faint galaxies.

The galaxy cluster shown in the image is known as SMACS 0723 and it appears as it did 4.6 billion years ago – the length of time it took for its light to reach the telescope. Light from the oldest-known galaxy in the image had been traveling for 13.1 billion years before it reached JWST.

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Galaxy cluster SMACS 0723 is a technicolor landscape when viewed in mid-infrared light by NASA’s James Webb Space Telescope. Compared to Webb’s near-infrared image at right, the galaxies and stars are awash in new colors. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The MIRI instrument’s ability to detect longer infrared wavelengths provides additional information in the image about the make-up of those galaxies. Mid-infrared light highlights dust, an important star-forming ingredient. In this image, red objects contain thick dust layers, while blue galaxies contain stars but not much dust. Green objects contain dust filled with hydrocarbons and other compounds. With these data, astronomers will be able to better understand the formation and growth of galaxies.

As impressive as this image is, the JWST team has plans to capture more deep field images using even longer exposure times. Keep up to date with the latest images and spectra from JWST throughout the school year at the Webb Space Telescope Resource Gallery.

How They Did It

The Webb telescope's ability to detect these objects in such great detail is enabled by its size, the way it observes the universe, and the unique technologies aboard. We went into more detail about how JWST works in a previous Teachable Moment, but below you’ll find a review of some of the important ways JWST was uniquely designed to capture these groundbreaking images.

Observing the Infrared

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Light waves get stretched as the universe expands similar to how this ink mark stretches out as the elastic is pulled. Get students modeling and exploring this effect with this standards-aligned math lesson. Credit: NASA/JPL-Caltech | + Expand image

The Webb telescope was built with instruments like NIRSpec and MIRI that are sensitive to light in the near- and mid-infrared wavelengths to detect some of the most distant objects in space.

As light from distant objects travels to Earth, the universe expands, something it’s been doing since the Big Bang. The waves that make up the light get stretched as the universe expands. Visible lightwaves from distant objects that you would be able to see with your eyes get stretched out so far that the longer wavelengths shift from visible light into infrared. Scientists refer to this phenomenon as redshift – and the farther away an object is, the more redshift it undergoes.

Gathering Light

The light from some of these distant objects has traveled so far that it is incredibly dim. To see such dim light, the Webb telescope was built to be extremely sensitive. On the Webb telescope, 18 hexagonal mirrors combine to form a massive primary mirror that is 21 feet (6.5 meters) across – six times the surface area of Hubble.

A dozen or so engineers stand in a towering open room clad in white smocks covering their entire bodies. Above them, and taking up a third of the room's space, is the reflective gold honeycomb-shaped set of mirrors for JWST. The NASA Goddard Space Center logo is reflected in the mirror.

The complete optical telescope element on display inside a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in 2017. Credits: NASA/Desiree Stover | › Full image and caption

To detect faint infrared light, the instruments inside the telescope have to be kept very cold, otherwise those infrared signals could get lost in the heat of the telescope. The spacecraft’s orbit and tennis-court-size sunshield keep light and heat from the Sun, Earth, and Moon from warming up its sensitive instruments. And the MIRI instrument, which needs to be even colder to capture mid-infrared wavelengths, is equipped with a special cryocooler.

The unique design and innovative techniques used by the James Webb Space Telescope are what made the first images possible. As the mission continues, more targets will be observed, more discoveries will be made, and more of our universe will unfold before our eyes.

“It’s not every day you can say you contributed to something that inspires the world in a positive way, but I believe that’s what JWST is doing for everyone of all ages,” said JPL engineer Analyn Schneider, who is the project manager for the telescope's MIRI instrument. “The telescope will help us learn more about our galaxy and the rest of the universe, and as a bonus we get these magnificent images. Learning is a big part of being in science and engineering and that’s what makes it interesting and challenging.”

Teach It

Bring the excitement of these far-off observations closer to home by using the following resources in your classroom or for remote instruction. Plus explore more related resources below including projects for students, galleries, and interactives.

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NASA's Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

TAGS: Stars & Galaxies, JWST, K-12 Education, Teaching

  • Lyle Tavernier
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A slightly oblong donut-shaped ring of glowing warm dust especially bright at spots on the top, left, and right surrounds a black hole.

Find out how scientists captured the first image of Sagittarius A*, why it's important, and how to turn it into a learning opportunity for students.


Our home galaxy, the Milky Way, has a supermassive black hole at its center, but we’ve never actually seen it – until now. The Event Horizon Telescope, funded by the National Science Foundation, has released the first image of our galactic black hole, Sagittarius A* (pronounced “Sagittarius A-star” and abbreviated Sgr A*).

Read on to find out how the image was acquired and learn more about black holes and Sagittarius A*. Then, explore resources to engage learners in the exciting topic of black holes.

How Black Holes Work

A black hole is a location in space with a gravitational pull so strong that nothing, not even light, can escape it. A black hole’s outer edge, called its event horizon, defines the spherical boundary where the velocity needed to escape exceeds the speed of light. Matter and radiation fall in, but they can’t get out. Because not even light can escape, a black hole is literally black. Contrary to their name’s implication, black holes are not empty. In fact, a black hole contains a great amount of matter packed into a relatively small space. Black holes come in various sizes and can exist throughout space.

We can surmise a lot about the origin of black holes from their size. Scientists know how some types of black holes form, yet the formation of others is a mystery. There are three different types of black holes, categorized by their size: stellar-mass, intermediate-mass, and supermassive black holes.

Stellar-mass black holes are found throughout our Milky Way galaxy and have masses less than about 100 times that of our Sun. They comprise one of the possible endpoints of the lives of high-mass stars. Stars are fueled by the nuclear fusion of hydrogen, which forms helium and other elements deep in their interiors. The outflow of energy from the central regions of the star provides the pressure necessary to keep the star from collapsing under its own weight.

A bubble if gas is sucked into a swirl of glowing dust and gas around a black hole as hair-like whisps extend from the top and bottom of the swirl.

This illustration shows a binary system containing a stellar-mass black hole called IGR J17091-3624. The strong gravity of the black hole, on the left, is pulling gas away from a companion star on the right. This gas forms a disk of hot gas around the black hole, and the wind is driven off this disk. Image credit: NASA/CXC/M.Weiss | › Full image and caption

Once the fuel in the core of a high-mass star has completely burned out, the star collapses, sometimes producing a supernova explosion that releases an enormous amount of energy, detectable across the electromagnetic spectrum. If the star’s mass is more than about 25 times that of our Sun, a stellar-mass black hole can form.

Intermediate-mass black holes have masses between about 100 and 100,000 times that of our Sun. Until recently, the existence of intermediate-mass black holes had only been theorized. NASA’s Chandra X-ray Observatory has identified several intermediate-mass black hole candidates by observing X-rays emitted by the gas surrounding the black hole. The Laser Interferometer Gravitational Wave Observatory, or LIGO, funded by the National Science Foundation, detected the merger of two stellar-mass black holes with masses 65 and 85 times that of our Sun forming an intermediate-mass black hole of 142 solar masses. (Some of the mass was converted to energy and about nine solar masses were radiated away as gravitational waves.)

Supermassive black holes contain between a million and a billion times as much mass as a stellar-mass black hole. Scientists are uncertain how supermassive black holes form, but one theory is that they result from the combining of stellar-mass black holes.

A scale on the bottom shows mass (relative to the Sun) from 1 to 1 million and beyond. Stellar-mass black holes are shown on the left side of the scale between about 10 and 100 solar masses, followed on the right by intermediate-mass black holes from 100 to over 100,000 stellar masses followed by supermassive black holes from about 1 million on.

This chart illustrates the relative masses of super-dense cosmic objects, ranging from white dwarfs to the supermassive black holes encased in the cores of most galaxies. | › Full image and caption

Our local galactic center’s black hole, Sagittarius A*, is a supermassive black hole with a mass of about four million suns, which is fairly small for a supermassive black hole. NASA’s Hubble Space Telescope and other telescopes have determined that many galaxies have supermassive black holes at their center.

A bright-white collection of stars is surrounded by a berry colored swirl of stellar dust and stars.

This image shows the center of the Milky Way galaxy along with a closer view of Sagittarius A*. It was made by combining X-ray images from NASA's Chandra X-ray Observatory (blue) and infrared images from the agency's Hubble Space Telescope (red and yellow). The inset shows Sgr A* in X-rays only, covering a region half a light year wide. Image credit: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI | › Full image and caption

Why They're Important

Black holes hold allure for everyone from young children to professional astronomers. For astronomers, in particular, learning about Sagittarius A* is important because it provides insights into the formation of our galaxy and black holes themselves.

Understanding the physics of black hole formation and growth, as well as their surrounding environments, gives us a window into the evolution of galaxies. Though Sagittarius A* is more than 26,000 light years (152 quadrillion miles) away from Earth, it is our closest supermassive black hole. Its formation and physical processes influence our galaxy as galactic matter continually crosses the event horizon, growing the black hole’s mass.

Studying black holes also helps us further understand how space and time interact. As one gets closer to a black hole, the flow of time slows down compared with the flow of time far from the black hole. In fact, according to Einstein’s theory of general relativity, the flow of time slows near any massive object. But it takes an incredibly massive object, such as a black hole, to make an appreciable difference in the flow of time. There's still much to learn about what happens to time and space inside a black hole, so the more we study them, the more we can learn.

How Scientists Imaged Sagittarius A*

Black holes, though invisible to the human eye, can be detected by observing their effects on nearby space and matter. As a result of their enormous mass, black holes have extremely high gravity, which pulls in surrounding material at rapid speeds, causing this material to become very hot and emit X-rays.

This video explains how Sagittarius A* appears to still have the remnants of a blowtorch-like jet dating back several thousand years. Credit: NASA | Watch on YouTube

X-ray-detecting telescopes such as NASA’s Chandra X-ray Observatory can image the material spiraling into a black hole, revealing the black hole’s location. NASA’s Hubble Space Telescope can measure the speed of the gas and stars orbiting a point in space that may be a black hole. Scientists use these measurements of speed to determine the mass of the black hole. Hubble and Chandra are also able to image the effects of gravitational lensing, or the bending of light that results from the gravitational pull of black holes or other high-mass objects such as galaxies.

A bright central blob is surrounded by blue halos and whisps forming a sort of target pattern.

The thin blue bull's-eye patterns in this Hubble Space Telescope image are called "Einstein rings." The blobs are giant elliptical galaxies roughly 2 to 4 billion light-years away. And the bull's-eye patterns are created as the light from galaxies twice as far away is distorted into circular shapes by the gravity of the giant elliptical galaxies. | › Full image and caption

To directly image the matter surrounding a black hole, thus revealing the silhouette of the black hole itself, scientists from around the world collaborated to create the Event Horizon Telescope. The Event Horizon Telescope harnesses the combined power of numerous telescopes around the world that can detect radio-wave emissions from the sky to create a virtual telescope the size of Earth.

Narrated by Caltech’s Katie Bouman, this video explains how she and her fellow teammates at the Event Horizon Telescope project managed to take a picture of Sagittarius A* (Sgr A*), a beastly black hole lying 27,000 light-years away at the heart of our Milky Way galaxy. Credit: Caltech | Watch on YouTube

In 2019, the team released the first image of a black hole's silhouette when they captured the glowing gasses surrounding the M87* galactic black hole nearly 53 million light-years (318 quintillion miles) away from Earth. The team then announced that one of their next endeavors was to image Sagittarius A*.

A warm glowing ring surrounds an empty blackness.

Captured by the Event Horizon Telescope in 2019, this image of the the glowing gasses surrounding the M87* black hole, was the first image ever captured of a black hole. Image credit: Event Horizon Telescope Collaboration | + Expand image

To make the newest observation, the Event Horizon Telescope focused its array of observing platforms on the center of the Milky Way. A telescope array is a group of telescopes arranged so that, as a set, they function similarly to one giant telescope. In addition to the telescopes used to acquire the M87* image, three additional radio telescopes joined the array to acquire the image of Sagittarius A*: the Greenland Telescope, the Kitt Peak 12-meter Telescope in Arizona, and the NOrthern Extended Millimeter Array, or NOEMA, in France.

This image of the center of our Milky Way galaxy representing an area roughly 400 light years across, has been translated into sound. Listen for the different instruments representing the data captured by the Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope. The Hubble data outline energetic regions where stars are being born, while Spitzer's data captures glowing clouds of dust containing complex structures. X-rays from Chandra reveal gas heated to millions of degrees from stellar explosions and outflows from Sagittarius A*. Credit: Chandra X-ray Observatory | Watch on YouTube

The distance from the center of Sagittarius A* to its event horizon, a measurement known as the Schwarzschild radius, is enormous at seven million miles (12,000,000 kilometers or 0.08 astronomical units). But its apparent size when viewed from Earth is tiny because it is so far away. The apparent Schwarzschild radius for Sagittarius A* is 10 microarcseconds, about the angular size of a large blueberry on the Moon.

Acquiring a good image of a large object that appears tiny when viewed from Earth requires a telescope with extraordinarily fine resolution, or the ability to detect the smallest possible details in an image. The better the resolution, the better the image and the more detail the image will show. Even the best individual telescopes or array of telescopes at one location do not have a good enough resolution to image Sagittarius A*.

A dense field of stars like grains of sand is surrounded by wispy clouds of glowing gas and dust.

This image captured by NASA's Hubble Space Telescope shows the star-studded center of the Milky Way towards the constellation of Sagittarius. Even though you can't see our galaxy's central black hole directly, you might be able to pinpoint its location based on what you've learned about black holes thusfar. Image credit: NASA, ESA, and G. Brammer | › Full image and caption

The addition of the 12-meter Greenland Telescope, though a relatively small instrument, widened the diameter, or aperture, of the Event Horizon Telescope to nearly the diameter of Earth. And NOEMA – itself an array of twelve 15-meter antennas with maximum separation of 2,500 feet (760 meters) – helped further increase the Event Horizon Telescope’s light-gathering capacity.

Altogether, when combined into the mighty Event Horizon Telescope, the virtual array obtained an image of Sagittarius A* spanning about 50 microarcseconds, or about 1/13th of a billionth the span of the night sky.

A slightly oblong donut-shaped ring of glowing warm dust especially bright at spots on the top, left, and right surrounds a black hole.

Sagittarius A* is more than 26,000 light years (152 quadrillion miles) away from Earth and has the mass of 4 million suns. Image credit: Event Horizon Telescope | › Full image and caption

While the Event Horizon Telescope was busy capturing the stunning radio image of Sagittarius A*, an additional worldwide contingent of astronomical observatories was also focused on the black hole and the region surrounding it. The aim of the team, known as the Event Horizon Telescope Multiwavelength Science Working Group, was to observe the black hole in other parts of the electromagnetic spectrum beyond radio. As part of the effort, X-ray data were collected by NASA’s Chandra X-ray Observatory, Nuclear Spectroscopic Telescope (NuSTAR), and Neil Gehrels Swift Observatory, additional radio data were collected by the East Asian Very Long-Baseline Interferometer (VLBI) network and the Global 3 millimeter VLBI array, and infrared data were collected by the European Southern Observatory’s Very Large Telescope.

The data from these multiple platforms will allow scientists to continue building their understanding of the behavior of Sagittarius A* and to refine their models of black holes in general. The data collected from these multiwavelength observations are crucial to the study of black holes, such as the Chandra data revealing how quickly material falls in toward the disk of hot gas orbiting the black hole’s event horizon. Data such as these will hopefully help scientists better understand black hole accretion, or the process by which black holes grow.

Teach It

Check out these resources to bring the real-life STEM of black holes into your teaching, plus learn about opportunities to involve students in real astronomy research.

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Across the NASA-Verse


This Teachable Moment was created in partnership with NASA’s Universe of Learning. Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

TAGS: Black hole, Milky Way, galaxy, universe, stars, teachers, educators, lessons, Teachable Moments, K-12, science

  • Ota Lutz
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Animation showing a total lunar eclipse. Credit: NASA Goddard Media Studios

There’s no better time to learn about the Moon than during a lunar eclipse. Here’s how eclipses work, what to expect, and how to get students engaged.


A full moon is always a good reason to go outside and look up, but a total or partial lunar eclipse is an awe-inspiring site that gives students a great opportunity to engage in practical sky watching. Whether it’s the Moon's reddish hue during a total lunar eclipse or the "bite" taken out of the Moon during a partial lunar eclipse, there's always something exciting to observe during these celestial events. Read on to see what to expect during the next lunar eclipse. Plus, explore resources you can use at home or in the classroom to teach students about moon phases, craters, and more!

How It Works

Side-by-side images showing how the Moon, Sun and Earth align during an lunar eclipse versus a standard full moon

These side-by-side graphics show how the Moon, Sun, and Earth align during a lunar eclipse (left) versus a non-eclipse full moon (right). Credit: NASA Goddard Visualization Studio | + Enlarge image

Eclipses can occur when the Sun, the Moon and Earth align. Lunar eclipses can only happen during the full moon phase, when the Moon and the Sun are on opposite sides of Earth. At that point, the Moon could move into the shadow cast by Earth, resulting in a lunar eclipse. However, most of the time, the Moon’s slightly tilted orbit brings it above or below the shadow of Earth.

The time period when the Moon, Earth and the Sun are lined up and on the same plane – allowing for the Moon to pass through Earth’s shadow – is called an eclipse season. Eclipse seasons last about 34 days and occur just shy of every six months. When a full moon occurs during an eclipse season, the Moon travels through Earth’s shadow, creating a lunar eclipse.

Graphic showing the alignment of the Sun, Earth and Moon when a full moon occurs during an eclipse season versus a non-eclipse season

When a full moon occurs during an eclipse season, the Moon travels through Earth's shadow, creating a lunar eclipse. Credit: NASA/JPL-Caltech | + Enlarge image

Unlike solar eclipses, which require special glasses to view and can only be seen for a few short minutes in a very limited area, a total lunar eclipse can last over an hour and be seen by anyone on the nighttime side of Earth – as long as skies are clear!

Why It’s Important

Lunar eclipses have long played an important role in understanding Earth and its motions in space.

In ancient Greece, Aristotle noted that the shadows on the Moon during lunar eclipses were round, regardless of where an observer saw them. He realized that only if Earth were a spheroid would its shadows be round – a revelation that he and others had many centuries before the first ships sailed around the world.

Earth wobbles on its axis like a spinning top that’s about to fall over, a phenomenon called precession. Earth completes one wobble, or precession cycle, over the course of 26,000 years. Greek astronomer Hipparchus made this discovery by comparing the position of stars relative to the Sun during a lunar eclipse to those recorded hundreds of years earlier. A lunar eclipse allowed him to see the stars and know exactly where the Sun was for comparison – directly opposite the Moon. If Earth didn’t wobble, the stars would appear to be in the same place they were hundreds of years earlier. When Hipparchus saw that the stars’ positions had indeed moved, he knew that Earth must wobble on its axis!

Additionally, modern-day astronomers have used ancient eclipse records and compared them with computer simulations. These comparisons helped scientists determine the rate at which Earth’s rotation is slowing.

What to Expect

The Moon passes through two distinct parts of Earth’s shadow during a lunar eclipse. The outer part of the cone-shaped shadow is called the penumbra. The penumbra is less dark than the inner part of the shadow because it’s penetrated by some sunlight. (You have probably noticed that some shadows on the ground are darker than others, depending on how much outside light enters the shadow; the same is true for the outer part of Earth’s shadow). The inner part of the shadow, known as the umbra, is much darker because Earth blocks additional sunlight from entering the umbra.

Note: Times and locations below are for the eclipse that occurred on May 15-16, 2022. Check back in October for times and locations for the upcoming eclipse on November 8, 2022.

Here's what to expect during the total lunar eclipse on May 15-16, 2022, which will be visible in North and South America, as well as in Africa, and Europe. Viewers in the most western parts of the continental U.S. will have to wait until the Moon rises above the horizon to see the eclipse, which will already be underway.

At 9:32 p.m. EDT (8:32 p.m. CDT), the edge of the Moon will begin entering the penumbra. The Moon will dim very slightly for the next 56 minutes as it moves deeper into the penumbra. Because this part of Earth’s shadow is not fully dark, you may only notice some dim shading (if anything at all) on the Moon near the end of this part of the eclipse. Should you decide to skip this part of the eclipse, you won’t miss much.

Graphic showing the positions of the Moon, Earth and Sun during a partial lunar eclipse

During a total lunar eclipse, the Moon first enters into the penumbra, or the outer part of Earth's shadow, where the shadow is still penetrated by some sunlight. Credit: NASA | + Enlarge image

At 10:28 p.m. EDT (9:28 p.m. CDT), the edge of the Moon will begin entering the umbra. As the Moon moves into the darker shadow, significant darkening will be noticeable. Some say that during this part of the eclipse, the Moon looks as if it has had a bite taken out of it. That “bite” gets bigger and bigger as the Moon moves deeper into the shadow. During this part of the eclipse, viewers in the eastern, central, and southwestern U.S. will see the Moon as it moves into the umbra. West Coast viewers, keep your eyes on the eastern horizon for the Moon to rise sometime between 7:20 and 8:40 PDT, depending on your location.

The Moon as seen during a partial lunar eclipse

As the Moon starts to enter into the umbra, the inner and darker part of Earth's shadow, it appears as if a bite has been taken out of the Moon. This "bite" will grow until the Moon has entered fully into the umbra. Credit: NASA | + Enlarge image

At 11:29 p.m. EDT (10:29 p.m. CDT), the Moon will be completely inside the umbra, marking the beginning of the total lunar eclipse, also known as totality. Viewers in the most northwestern parts of the continental U.S. will see the Moon rise as totality is beginning.

Graphic showing the Moon inside the umbra

The total lunar eclipse starts once the moon is completely inside the umbra. And the moment of greatest eclipse happens with the Moon is halfway through the umbra as shown in this graphic. Credit: NASA | + Enlarge image

The moment of greatest eclipse, when the Moon is halfway through its path across the umbra, occurs at 12:12 a.m. EDT (11:12 p.m. CDT). As the Moon moves completely into the umbra – the part of the eclipse known as totality – something interesting happens: The Moon begins to turn reddish-orange. The reason for this phenomenon? Earth’s atmosphere. As sunlight passes through it, the small molecules that make up our atmosphere scatter blue light, which is why the sky appears blue. This leaves behind mostly red light that bends, or refracts, into Earth’s shadow. We can see the red light during an eclipse as it falls onto the Moon in Earth’s shadow. This same effect is what gives sunrises and sunsets a reddish-orange color.

The Moon as seen during a total lunar eclipse at the point of greatest eclipse

As the Moon moves completely into the umbra, it turns a reddish-orange color. Credit: NASA | + Enlarge image

A variety of factors affect the appearance of the Moon during a total lunar eclipse. Clouds, dust, ash, photochemical droplets and organic material in the atmosphere can change how much light is refracted into the umbra. The potential for variation provides a great opportunity for students to observe and classify the lunar eclipse based on its brightness. Details can be found below in the Teach It section.

At 12:54 a.m. EDT (11:54 p.m. CDT), the edge of the Moon will begin exiting the umbra and moving into the opposite side of the penumbra, reversing the “bite” pattern seen earlier.

At 1:55 a.m. EDT (12:55 a.m. CDT), the Moon will be completely outside of the umbra and will begin exiting the penumbra until the eclipse officially ends at 2:50 a.m. EDT (1:50 a.m. CDT).

Teach It

Ask students to observe the lunar eclipse and evaluate the Moon’s brightness using the Danjon Scale of Lunar Eclipse Brightness. The Danjon scale illustrates the range of colors and brightness the Moon can take on during a total lunar eclipse and is a tool observers can use to characterize the appearance of an eclipse. View the lesson guide here. After the eclipse, have students compare and justify their evaluations of the eclipse.

Use these standards-aligned lessons and related activities to get your students excited about the eclipse, moon phases, and Moon observations.

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TAGS: Lunar Eclipse, Moon, Super Blue Blood Moon, Observe the Moon, Eclipse, K-12, Classroom Activities, Teaching

  • Lyle Tavernier
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A small piece of the ISS is visible in the top corner of this view looking down from space station over Earth. A large cloud of dust takes half the view over Earth's surface.

A data map overlaid on the globe shows thick swirls of dust traveling from West Africa, across the Atlantic Ocean and all the way to the Caribbean and Southern U.S.

Learn about the role that dust plays in Earth's climate, why scientists are interested in studying dust from space, and how to engage students in the science with STEM resources from JPL.


A NASA instrument launched to the International Space Station this summer will explore how dust impacts global temperatures, cloud formation, and the health of our oceans. The Earth Surface Mineral Dust Source Investigation, or EMIT, is the first instrument of its kind, designed to collect measurements from space of some of the most arid regions on Earth to understand the composition of soils that generate dust and the larger role dust plays in climate change.

Read on to find out how the instrument works and why scientists are hoping to learn more about the composition of dust. Then, explore how to bring the science into your classroom with related climate lessons that bridge physical sciences with engineering practices.

Why It’s Important

Scientists have long studied the movements of dust. The fact that dust storms can carry tiny particles great distances was reported in the scientific literature nearly two centuries ago by none other than Charles Darwin as he sailed across the Atlantic on the HMS Beagle. What still remains a mystery all these years later is what that dust is made of, how it moves, and how that affects the health of our planet.

For example, we now know that dust deposited on snow speeds up snow melt even more than increased air temperature. That is to say, that dust traveling to cold places can cause increased snow melt.

Sharp mountain peaks are covered in splotches of snow with a fine coating of dust visible on top of the snow.

A coating of dust on snow speeds the pace of snowmelt in the spring. Credit: NASA | + Expand image

Dust can affect air temperatures as well. For example, dust with more iron absorbs light and can cause the air to warm, while dust with less iron reflects light and is responsible for local cooling. Iron in dust can also act as a fertilizer for plankton in oceans, supplying them with nutrients needed for growth and reproduction.

A plume of dust eminates from over the Copper River in Alaska, spreading out as this series of overhead satellite images progresses.

A plume of dust is shown emanating from over Alaska's Copper River in October 2016 in these images captured by the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument on NASA’s Terra and Aqua satellites. Dust storms play a key role in fueling phytoplankton blooms by delivering iron to the Gulf of Alaska. Credit: NASA | › Full image and caption

Floating dust potentially alters the composition of clouds and how quickly or slowly they form, which can ultimately impact weather patterns, including the formation of hurricanes. That’s because clouds need particles to act as seeds around which droplets of moisture in the atmosphere can form. This process of coalescing water particles, called nucleation, is one factor in how clouds form.

An overhead view of a swirl of clouds mixed with a streak of dust like a swirl of milk froth in a cappuccino

A swirl of dust mixes with the clouds in a low-pressure storm over the Gobi desert between Mongolia and China. This image was captured by the MODIS instrument on the Terra satellite in May 2019. Credit: NASA | › Full image and caption

Thanks to EMIT, we’ll take the first steps in understanding how the movements of dust particles contribute to local and global changes in climate by producing “mineral maps”. These mineral maps will reveal differences in the chemical makeup of dust, providing essential information to help us model the way dust can transform Earth’s climate.

› Learn more about what EMIT will do from JPL News

How It Works

NASA has been exploring how dust moves across the globe by combining on-the-ground field studies with cutting-edge technology.

Dr. Olga Kalashnikova, an aerosol scientist at NASA's Jet Propulsion Laboratory and a co-investigator for EMIT, has been using satellite data to study atmospheric mineral dust for many years, including tracking the movements of dust and investigating trends in the frequency of dust storms.

As Dr. Kalashnikova describes, “From the ground, we can see what types of dusts are lifted into the atmosphere by dust storms on a local scale, but with EMIT, we can understand how they differ and where they originally came from.”

EMIT is the first instrument designed to observe a key part of the mineral dust cycle from space, allowing scientists to track different dust compositions on a global scale, instead of in just one region at a time. To understand dust’s impact on Earth’s climate, scientists will use EMIT to answer key questions, including:

  • How does dust uplifted in the atmosphere alter global temperatures?
  • What role do dusts play in fertilizing our oceans when they are deposited?
  • How do dust particles in the atmosphere affect cloud nucleation; the process by which clouds are ‘seeded’ and begin to coalesce into larger clouds?
A picture of the EMIT instrument, shaped like a small megaphone, is overlaid on an picture of the International Space Station flying above Earth.

The EMIT instrument will fly aboard the International Space Station, which orbits Earth about once every 90 minutes, completing about 16 orbits per day. Credit: NASA | + Expand image

To achieve its objectives, EMIT will spend 12 months collecting what are called “hyperspectral images” of some of the most arid regions of our planet selected by scientists and engineers as areas of high dust mobility, such as Northern Africa, the Middle East, and the American Southwest.

These images are measurements of light reflected from the Earth below, calibrated to the distinct patterns, or spectra, of light we see when certain minerals are present. The EMIT team has identified 10 minerals that are most common, including gypsum, hematite, and kaolinite.

Bands of satellite images looking at a seciton of Earth are highlighted in different colors to reveal different concentrations of minerals.

This example spectra shows how scientists will be able to identify different concentrations of minerals and elements in data collected by EMIT. Credit: NASA/JPL-Caltech | + Expand image

Why are these minerals important? One key reason is the presence or absence of the element iron, found in some minerals but not others.

Dr. Bethany Ehlmann is a planetary scientist and co-investigator for the EMIT project at Caltech and explains that when it comes to heating, “a little bit of iron goes a long way.” Iron in minerals absorbs visible and infrared light, meaning that even if only a small amount is present, it will result in a much warmer dust particle. Large amounts of warm dust in our atmosphere may have an impact on temperatures globally since those dust particles radiate heat as they travel, sometimes as far as across oceans!

Collecting images from space is, of course, no easy task, especially when trying to look only at the ground below. Yet it does allow scientists to get a global picture that's not possible to capture from the ground. Field studies allow us to take individual samples from tiny places of interest, but from space, we can scan the entire planet in remote places where no scientist can visit.

Of course, there are some complications in trying to study the light reflected off the surface of Earth, such as interference from clouds. To prevent this problem, the EMIT team plans to collect data at each location several times to ensure that the images aren’t being obscured by clouds between the instrument and the minerals we’re looking for.

The data collected by EMIT will provide a map of the compositions of dust from dry, desert environments all over the world, but the team involved won’t stop there. Knowing more about what the dust is made of sets the stage for a broader understanding of a few more of the complex processes that make up our global climate cycle. Upon completion of this study, EMIT's mineral maps will support further campaigns to complete our global dust picture. For example, NASA hopes to couple the data from EMIT with targeted field campaigns, in which scientists can collect wind-blown dust from the ground to learn more about where dust particles move over time and answer questions about what types of dust are on the go.

Furthermore, missions such as the Multiangle Imager for Aerosols, or MAIA, will allow us to better understand the effects of these dust particles on air-quality and public health.

Teach it

Studying Earth’s climate is a complex puzzle, consisting of many trackable features. These can range from sea level to particles in our atmosphere, but each makes a contribution to measuring the health of our planet. Bring EMIT and NASA Earth Science into your classroom with these lessons, articles, and activities to better understand how we’re exploring climate change.

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TAGS: Earth, climate, geology, weather, EMIT, Teachers, Classroom, Lessons, Earth Science, Climate Change, Dust, Global Warming, Educators, K-12, Teachable Moments, Climate TM

  • Brandon Rodriguez
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The Millennium Falcon takes on TIE fighters in a scene from 'Star Wars: The Force Awakens.'

Science fiction meets science fact in this Star Wars inspired Teachable Moment all about ion propulsion and Newton’s Laws.

In the News

What do "Star Wars," NASA's Dawn spacecraft and Newton's Laws of Motion have in common? An educational lesson that turns science fiction into science fact using spreadsheets – a powerful tool for developing the scientific models addressed in the Next Generation Science Standards. Keep reading to learn more and find out how to get students wielding the force.

Why It's Important

The TIE (Twin Ion Engine) fighter is a staple of the "Star Wars" universe. Darth Vader flew one in "A New Hope." Poe Dameron piloted one in "The Force Awakens." And many, many Imperial pilots met their fates in them. While the fictional TIE fighters in "Star Wars" flew a long time ago in a galaxy far, far away, ion engines are a reality in this galaxy today – and have a unique connection to NASA’s Jet Propulsion Laboratory.

Launched in 1998, the first spacecraft to use an ion engine was Deep Space 1, which flew by asteroid 9969 Braille and comet Borrelly. Fueled by the success of Deep Space 1, engineers at JPL set forth to develop the next spacecraft that would use ion propulsion. This mission, called Dawn, would take ion-powered spacecraft to the next level by allowing Dawn to go into orbit twice – around the two largest objects in the asteroid belt: Vesta and Ceres.

How It Works

Ion engines rely on two principles that Isaac Newton first described in 1687. First, a positively charged atom (ion) is pushed out of the engine at a high velocity. Newton’s Third Law of Motion states that for every action there is an equal and opposite reaction, so then a small force pushes back on the spacecraft in the opposite direction – forward! According to Newton’s Second Law of Motion, there is a relationship between the force (F) exerted on an object, its mass (m) and its acceleration (a). The equation F=ma describes that relationship and tells us that the small force applied to the spacecraft by the exiting atom provides a small amount of acceleration to the spacecraft. Push enough atoms out, and you'll get enough acceleration to really speed things up.


Why is It Important?

Compared with traditional chemical rockets, ion propulsion is faster, cheaper and safer:

  • Faster: Spacecraft powered by ion engines can reach speeds of up to 90,000 meters per second (more than 201,000 mph!)
  • Cheaper: When it comes to fuel efficiency, ion engines can reach more than 90 percent fuel efficiency, while chemical rockets are only about 35 percent efficient.
  • Safer: Ion thrusters are fueled by inert gases. Most of them use xenon, which is a non-toxic, chemically inert (no risk of exploding), odorless, tasteless and colorless gas.

These properties make ion propulsion a very attractive solution when engineers are designing spacecraft. While not every spacecraft can use ion propulsion – some need greater rates of acceleration than ion propulsion can provide – the number and types of missions using these efficient engines is growing. In addition to being used on the Dawn spacecraft and communication satellites orbiting Earth, ion propulsion could be used to boost the International Space Station into higher orbits and will likely be a part of many future missions exploring our own solar system.

Teach It

Newton’s Laws of Motion are an important part of middle and high school physical science and are addressed specifically by the Next Generation Science Standards as well as Common Core Math standards. The lesson "Ion Propulsion: Using Spreadsheets to Model Additive Velocity" lets students study the relationship between force, mass and acceleration as described by Newton's Second Law as they develop spreadsheet models that apply those principles to real-world situations.

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This feature was originally published on May 3, 2016.

TAGS: May the Fourth, Star Wars Day, F=ma, ion propulsion, Dawn, Deep Space 1, lesson, classroom activity, NGSS, Common Core Math

  • Lyle Tavernier
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Collage of spacecraft featured in the 2022 NASA Pi Day Challenge

Graphic showing the various spacecraft featured in the 2022 NASA Pi Day Challenge overlaid with text that reads NASA Pi Day Challenge Answers

Learn about pi and some of the ways the number is used at NASA. Then, dig into the science behind the Pi Day Challenge.


Update: March 15, 2022 – The answers are here! Visit the NASA Pi Day Challenge slideshow to view the illustrated answer keys for each of the problems in the 2022 challenge.

In the News

No matter what Punxsutawney Phil saw on Groundhog Day, a sure sign that spring approaches is Pi Day. Celebrated on March 14, it’s the annual holiday that pays tribute to the mathematical constant pi – the number that results from dividing any circle's circumference by its diameter.

Every year, Pi Day gives us a reason to not only celebrate the mathematical wonder that helps NASA explore the universe, but also to enjoy our favorite sweet and savory pies. Students can join in the fun by using pi to explore Earth and space themselves in our ninth annual NASA Pi Day Challenge.

Read on to learn more about the science behind this year's challenge and find out how students can put their math mettle to the test to solve real problems faced by NASA scientists and engineers as we explore Earth, the Moon, Mars, and beyond!
Infographic of all of the Pi in the Sky 9 graphics and problems

Visit the Pi in the Sky 9 lesson page to explore classroom resources and downloads for the 2022 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech | + Expand image

An spacecraft orbiting the Moon shines a laser into a dark crater.

This artist's concept shows the Lunar Flashlight spacecraft, a six-unit CubeSat designed to search for ice on the Moon's surface using special lasers. Image credit: NASA/JPL-Caltech | › Full image details

Dome-covered seismometer sits on the surface of Mars while clouds pass overhead.

Clouds drift over the dome-covered seismometer, known as SEIS, belonging to NASA's InSight lander, on Mars. Credit: NASA/JPL-Caltech. | › Full image and caption

The SWOT spacecraft passes over Florida, sending signals and collecting data.

This animation shows the collection of data over the state of Florida, which is rich with rivers, lakes and wetlands. Credits: NASA/JPL-Caltech | + Expand image

A spacecraft points to a star that has three planets orbiting it.

Illustration of NASA’s Transiting Exoplanet Survey Satellite (TESS). Credits: NASA | + Expand image

How It Works

Dividing any circle’s circumference by its diameter gives you an answer of pi, which is usually rounded to 3.14. Because pi is an irrational number, its decimal representation goes on forever and never repeats. In 2021, a supercomputer calculated pi to more than 62 trillion digits. But you might be surprised to learn that for space exploration, NASA uses far fewer digits of pi.

Here at NASA, we use pi to understand how much signal we can receive from a distant spacecraft, to calculate the rotation speed of a Mars helicopter blade, and to collect asteroid samples. But pi isn’t just used for exploring the cosmos. Since pi can be used to find the area or circumference of round objects and the volume or surface area of shapes like cylinders, cones, and spheres, it is useful in all sorts of ways. Architects use pi when designing bridges or buildings with arches; electricians use pi when calculating the conductance of wire; and you might even want to use pi to figure out how much frozen goodness you are getting in your ice cream cone.

In the United States, March 14 can be written as 3.14, which is why that date was chosen for celebrating all things pi. In 2009, the U.S. House of Representatives passed a resolution officially designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi. And that's precisely what the NASA Pi Day Challenge is all about!

The Science Behind the 2022 NASA Pi Day Challenge

This ninth installment of the NASA Pi Day Challenge includes four brain-busters that get students using pi to measure frost deep within craters on the Moon, estimate the density of Mars’ core, calculate the water output from a dam to assess its potential environmental impact, and find how far a planet-hunting satellite needs to travel to send data back to Earth.

Read on to learn more about the science and engineering behind the problems or click the link below to jump right into the challenge.

› Take the NASA Pi Day Challenge

› Educators, get the lesson here!

Lunar Logic

NASA’s Lunar Flashlight mission is a small satellite that will seek out signs of frost in deep, permanently shadowed craters around the Moon’s south pole. By sending infrared laser pulses to the surface and measuring how much light is reflected back, scientists can determine which areas of the lunar surface contain frost and which are dry. Knowing the locations of water-ice on the Moon could be key for future crewed missions to the Moon, when water will be a precious resource. In Lunar Logic, students use pi to find out how much surface area Lunar Flashlight will measure with a single pulse from its laser.

Core Conundrum

Since 2018, the InSight lander has studied the interior of Mars by measuring vibrations from marsquakes and the “wobble” of the planet as it rotates on its axis. Through careful analysis of the data returned from InSight, scientists were able to measure the size of Mars’ liquid core for the first time and estimate its density. In Core Conundrum, students use pi to do some of the same calculations, determining the volume and density of the Red Planet’s core and comparing it to that of Earth’s core.

Dam Deduction

The Surface Water and Ocean Topography, or SWOT mission will conduct NASA's first global survey of Earth's surface water. SWOT’s state-of-the-art radar will measure the elevation of water in major lakes, rivers, wetlands, and reservoirs while revealing unprecedented detail on the ocean surface. This data will help scientists track how these bodies of water are changing over time and improve weather and climate models. In Dam Deduction, students learn how data from SWOT can be used to assess the environmental impact of dams. Students then use pi to do their own analysis, finding the powered output of a dam based on the water height of its reservoir and inferring potential impacts of this quick-flowing water.

Telescope Tango

The Transiting Exoplanet Survey Satellite, or TESS, is designed to survey the sky in search of planets orbiting bright, nearby stars. TESS does this while circling Earth in a unique, never-before-used orbit that brings the spacecraft close to Earth about once every two weeks to transmit its data. This special orbit keeps TESS stable while giving it an unobstructed view of space. In its first two years, TESS identified more than 2,600 possible exoplanets in our galaxy with thousands more discovered during its extended mission. In Telescope Tango, students will use pi to calculate the distance traveled by TESS each time it sends data back to Earth.

Teach It

Celebrate Pi Day by getting students thinking like NASA scientists and engineers to solve real-world problems in NASA Pi Day Challenge. Completing the problem set and reading about other ways NASA uses pi is a great way for students to see the importance of the M in STEM.

Pi Day Resources

Plus, join the conversation using the hashtag #NASAPiDayChallenge on Facebook, Twitter, and Instagram.

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TAGS: Pi Day, Pi, Math, NASA Pi Day Challenge, Moon, Lunar Flashlight, Mars, InSight, Earth, Climate, SWOT, Exoplanets, Universe, TESS, Teachers, Educators, Parents, Students, Lessons, Activities, Resources, K-12

  • Lyle Tavernier
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Just beyond the wing of a plane, the edge of a tall glacier is visible through the plane's window. At the bottom of the glacier, bits of ice surround an elliptical pool of brown water at the glacier's edge.

Explore how the OMG mission discovered more about what's behind one of the largest contributors to global sea level rise. Plus, learn what it means for communities around the world and how to get students engaged.


After six years investigating the effects of warming oceans on Greenland's ice sheet, the Oceans Melting Greenland, or OMG, mission has concluded. This airborne and seaborne mission studied how our oceans are warming and determined that ocean water is melting Greenland’s glaciers as much as warm air is melting them from above.

Read on to learn more about how OMG accomplished its goals and the implications of what we learned. Then, explore educational resources to engage students in the science of this eye-opening mission.

Why It's Important

Global sea level rise is one of the major environmental challenges of the 21st century. As oceans rise, water encroaches on land, affecting populations that live along shorelines. Around the world – including U.S. regions along the Gulf of Mexico and Eastern Seaboard and in Alaska – residents are feeling the impact of rising seas. Additionally, freshwater supplies are being threatened by encroaching saltwater from rising seas.

Sea level rise is mostly caused by melting land ice (primarily glaciers), which adds water to the ocean, as well as thermal expansion, the increase in volume that occurs when water heats up. Both ice melt and thermal expansion result from rising global average temperatures on land and in the sea – one facet of climate change.

This short video explains why Greenland's ice sheets are melting and what it means for our planet. Credit: NASA/JPL-Caltech | Watch more from the Earth Minute series

Greenland’s melting glaciers contribute more freshwater to sea level rise than any other source, which is why the OMG mission set out to better understand the mechanisms behind this melting.

How We Did It

The OMG mission used a variety of instruments onboard airplanes and ships to map the ocean floor, measure the behemoth Greenland glaciers, and track nearby water temperature patterns.

Join JPL scientist Josh Willis as he and the NASA Oceans Melting Greenland (OMG) team work to understand the role that ocean water plays in melting Greenland’s glaciers. Credit: NASA/JPL-Caltech | Watch on YouTube

An animation shows a ship passing over the ocean directly in front of a glacier and scanning the sea floor followed by a plane flying overhead and scanning the air.

This animation shows how the OMG mission created a map of the ocean floor, known as a bathymetric map, to determine the geometry around Greenland's glaciers. Image credit: NASA/JPL-Caltech | + Expand image

An animation shows a plan flying over a glacier and scanning the ground below followed by a plane flying over the ocean shelf next to the glacier and dropping probes into the water.

This animation shows how the OMG mission used radar to measure changes in the thickness and retreat of Greenland's glaciers as well as probes to measure ocean temperature and salinity. Credit: NASA/JPL-Caltech | + Expand image

Early on, the mission team created a map of the ocean floor, known as a bathymetric map, by combining multibeam sonar surveys taken from ships and gravity measurements taken from airplanes. Interactions among glaciers and warming seas are highly dependent on the geometry of the ocean floor. For example, continental shelf troughs carved by glaciers allow pathways for water to interact with glacial ice. So understanding Greenland's local bathymetry was crucial to OMG's mission.

To locate the edges of Greenland's glaciers and measure their heights, the mission used a radar instrument known as the Glacier and Ice Surface Topography Interferometer. Every spring during the six-year OMG mission, the radar was deployed on NASA’s Gulfstream III airplane that flew numerous paths over Greenland’s more than 220 glaciers. Data from the instrument allowed scientists to determine how the thickness and area of the glaciers are changing over time.

Finally, to measure ocean temperature and salinity patterns, scientists deployed numerous cylindrical probes. These probes dropped from an airplane and fell through the water, taking measurements from the surface all the way to the ocean floor. Each probe relayed its information back to computers onboard the plane where ocean temperatures and salinity were mapped. Then, scientists took this data back to their laboratories and analyzed it for trends, determining temperature variations and circulation patterns.

What We Discovered

Prior to the OMG mission, scientists knew that warming air melted glaciers from above, like an ice cube on a hot day. However, glaciers also flow toward the ocean and break off into icebergs in a process called calving. Scientists had the suspicion that warmer ocean waters were melting the glaciers from below, causing them to break off more icebergs and add to rising seas. It wasn’t until they acquired the data from OMG, that they discovered the grim truth: Glaciers are melting from above and below, and warming oceans are having a significant effect on glacial melt.

This narrated animation shows warm ocean water is melting glaciers from below, causing their edges to break off in a process called calving. Credit: NASA | Watch on YouTube

What this means for our Earth's climate is that as we continue burning fossil fuels and contributing to greenhouse gas accumulation, the oceans, which store more than 90% of the heat that is trapped by greenhouse gases, will continue to warm, causing glaciers to melt faster than ever. As warming ocean water moves against glaciers, it eats away at their base, causing the ice above to break off. In other words, calving rates increase and sea level rises even faster.

Our oceans control our climate and affect our everyday lives, whether or not we live near them. With the pace of the melt increasing, our shorelines and nearby communities will be in trouble sooner than previously expected. And it’s not just the beaches that will be affected. If Greenland’s glaciers all melt, global sea levels will rise by over 24 feet (7.4 meters), bringing dramatic change to the landscapes of major cities around the world.

› Read more about OMG’s findings and how scientists are continuing their research through ongoing initiatives and projects.

Teach It

Check out these resources to bring the real-life STEM behind the mission into your teaching. With lessons for educators and student projects, engage students in learning about the OMG mission and NASA climate science.

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TAGS: Teachable Moment, Climate, Earth Science, Glaciers, Greenland, Ice, Sea Level Rise, Teachers, Educators, Parents, Lessons, Missions, Earth, Climate TM

  • Ota Lutz
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In the cleanroom at Northrop Grumman, a technician inspects the bellows between the hexagonal sections that make up the large honeycomb-shaped mirror on the Webb telescope.

Get a look into the science and engineering behind the largest and most powerful space telescope ever built while exploring ways to engage learners in the mission.


NASA is launching the largest, most powerful space telescope ever. The James Webb Space Telescope will look back at some of the earliest stages of the universe, gather views of early star and galaxy formation, and provide insights into the formation of planetary systems, including our own solar system.

Read on to learn more about what the space-based observatory will do, how it works, and how to engage learners in the science and engineering behind the mission.

What It Will Do

The James Webb Space Telescope, or JWST, was developed through a partnership between NASA and the European and Canadian space agencies. It will build upon and extend the discoveries made by the Hubble Space Telescope to help unravel mysteries of the universe. First, let's delve into what scientists hope to learn with the Webb telescope.

A look at the James Webb Space Telescope, its mission and the incredible technological challenge this mission presents. | Watch on YouTube

How Galaxies Evolve

What the first galaxies looked like and when they formed is not known, and the Webb telescope is designed to help scientists learn more about that early period of the universe. To better understand what the Webb telescope will study, it’s helpful to know what happened in the early universe, before the first stars formed.

The universe, time, and space all began about 13.8 billion years ago with the Big Bang. For the first few hundred-thousand years, the universe was a hot, dense flood of protons, electrons, and neutrons, the tiny particles that make up atoms. As the universe cooled, protons and neutrons combined into ionized hydrogen and helium, which had a positive charge, and eventually attracted all those negatively charged electrons. This process, known as recombination, occurred about 240,000 to 300,000 years after the Big Bang.

An ellipse is filled with speckled dark blue, green, and small yellow and red splotches.

This image shows the temperature fluctuations (shown as color differences) in the cosmic microwave background from a time when the universe was less than 400,000 years old. The image was captured by the Wilkinson Microwave Anisotropy Probe, or WMAP, which spent nine years, from 2001 to 2010, collecting data on the early universe. Credit: NASA | › Full image and caption | + Expand image

Light that previously couldn’t travel without being scattered by the dense ionized plasma of early particles could now travel freely. The very first form of light we can look back and see comes from this time and is known as the cosmic microwave background radiation. It is essentially a map of temperature fluctuations across the universe left behind from the Big Bang. The fluxuations give clues about the origin of galaxies and the large-scale structure of galaxies. There were still no stars in the universe at this time, so the next several hundred million years are known as the cosmic dark ages.

Current theory predicts that the earliest stars were big – 30 to 300 times the size of our Sun – and burned quickly, ending in supernova explosions after just a few million years. (For comparison, our Sun has a lifespan of about 10 billion years and will not go supernova.) Observing these luminous supernovae is one of the few ways scientists could study the earliest stars. That is vital to understanding the formation of objects such as the first galaxies.

By using the Webb telescope to compare the earliest galaxies with those of today, scientists hope to understand how they form, what gives them their shape, how chemical elements are distributed across galaxies, how central black holes influence their galaxies, and what happens when galaxies collide.

Learn how the James Webb Space Telescope's ability to look farther into space than ever before will bring newborn galaxies into view. | Watch on YouTube

How Stars and Planetary Systems Form

Stars and their planetary systems form within massive clouds of dust and gas. It's impossible to see into these clouds with visible light, so the Webb telescope is equipped with science instruments that use infrared light to peer into the hearts of stellar nurseries. When viewing these nurseries in the mid-infrared – as the Webb telescope is designed to do – the dust outside the dense star forming regions glows and can be studied directly. This will allow astronomers to observe the details of how stars are born and investigate why most stars form in groups as well as how planetary systems begin and evolve.

Plumes of red stellar dust shoot out from the top and bottom of a bright central disk.

This mosaic image is the sharpest wide-angle view ever obtained of the starburst galaxy, Messier 82 (M82). The galaxy is remarkable for its bright blue disk, webs of shredded clouds and fiery-looking plumes of glowing hydrogen blasting out of its central regions.Throughout the galaxy's center, young stars are being born 10 times faster than they are inside our entire Milky Way Galaxy. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA); Acknowledgment: J. Gallagher (University of Wisconsin), M. Mountain (STScI), and P. Puxley (National Science Foundation) | › Full image and caption | + Expand image

How Exoplanets and Our Solar System Evolve

Collage of futuristic posters depicting explorers on various exoplanets.

As we make more discoveries about exoplanets, artists at NASA are imagining what future explorers might encounter on these faraway worlds as part of the Exoplanet Travel Bureau poster series. Credit: NASA | › View and download the posters | + Expand image

The first planet outside our solar system, or exoplanet, was discovered in 1992. Since then, scientists have found thousands more exoplanets and estimate that there are hundreds of billions in the Milky Way galaxy alone. There are many waiting to be discovered and there is more to learn about the exoplanets themselves, such as what makes up their atmospheres and what their weather and seasons may be like. The Webb telescope will help scientists do just that.

In our own solar system, the Webb telescope will study planets and other objects to help us learn more about our solar neighborhood. It will be able to complement studies of Mars being carried out by orbiters, landers, and rovers by searching for molecules that may be signs of past or present life. It is powerful enough to identify and characterize icy comets in the far reaches of our solar system. And it can be used to study places like Saturn, Uranus, and Neptune while there are no active missions at those planets.

How It Works

The Webb telescope has unique capabilities enabled by the way it views the universe, its size, and the new technologies aboard. Here's how it works.

Peering Into the Infrared

To see ancient, distant galaxies, the Webb telescope was built with instruments sensitive to light in the near- and mid-infrared wavelengths.

Light leaving these galaxies can take billions of years to reach Earth, so when we see these objects, we’re actually seeing what they looked like in the past. The farther something is from Earth, the farther back in time it is when we observe it. So when we look at light that left objects 13.5 billion years ago, we're seeing what happened in the early universe.

A sideways funnel that fans out at one end encapsulates an illustration of the history of the universe starting with the Big Bang 13.7 billion years ago through the first stars, the development of galaxies, and accelerated expansion.

An illustrated timeline of the universe. Credit: WMAP | + Expand image

As light from distant objects travels to Earth, the universe continues to expand, something it’s been doing since the Big Bang. The waves that make up the light get stretched as the universe expands. You can see this effect in action by making an ink mark on a rubber band and observing how the mark stretches out when you pull on the rubber band.

https://www.jpl.nasa.gov/edu/images/redshift_demo.gif

Light waves get stretched as the universe expands similar to how this ink mark stretches out as the elastic is pulled. Get students modeling and exploring this effect with this standards-aligned math lesson. Credit: NASA/JPL-Caltech | + Expand image

What this means for light coming from distant galaxies is that the visible lightwaves you would be able to see with your eyes get stretched out so far that the longer wavelengths shift from visible light into infrared. Scientists refer to this phenomenon as redshift – and the farther away an object is, the more redshift it undergoes.

Webb telescope’s infrared sensing equipment will give scientists the chance to study some of the earliest stars that exploded in supernova events, creating the elements necessary to build planets and form life.

Gathering Light

The first stars were massive, their life cycles ending in supernova explosions. The light from these explosions has traveled so far that it is incredibly dim. This is due to the inverse square law. You experience this effect when a room appears to get darker as you move away from a light source.

To see such dim light, the Webb telescope needs to be extremely sensitive. A telescope’s sensitivity, or its ability to detect faint signals, is related to the size of the mirror it uses to gather light. On the Webb telescope, 18 hexagonal mirrors combine to form a massive primary mirror that is 21 feet (6.5 meters) across.

A technician in a white smock stands up in a gap between several large hexagonal mirrors forming a honeycomb shape.

A technician inspects the Webb telescope's honeycomb-shaped mirror. The telescope's primary mirror is 21 feet (6.5 meters) across and is made up of 18 smaller hexagonal mirrors that must fold for launch and unfurl after the telescope reaches its orbit in space. Credit: NASA/MSFC/David Higginbotham/Emmett Given | › Full image and caption | + Expand image

Compared with the Hubble Space Telescope’s eight-foot (2.4 meter) diameter mirror, this gives the Webb telescope more than six times the surface area to collect those distant particles of light known as photons. Hubble’s famous Ultra Deep Field observation captured images of incredibly faint, distant galaxies by pointing at a seemingly empty spot in space for 16 days, but the Webb telescope will be able to make a similar observation in just seven hours.

Colorful spirals, disks, and stars of various sizes and shapes appear against the blackness of space like sprinkles on a cake.

This image, called the Hubble Ultra Deep Field, shows 28 of the more than 500 young galaxies that existed when the universe was less than 1 billion years old. Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz) | › Full image and caption | + Expand image

Keeping Cool

The Webb Telescope gathers its scientific data as infrared light. To detect the faint signals of objects billions of light years away, the instruments inside the telescope have to be kept very cold, otherwise those infrared signals could get lost in the heat of the telescope. Engineers accounted for this with a couple of systems designed to get the instruments cold and keep them cold.

The Webb telescope's orbit around the Sun – sitting about 1 million miles (1.5 million kilometers) from Earth at Lagrange point 2 – keeps the spacecraft pretty far from our planet's heat, but even that’s not enough. To further reduce the temperature on the instruments, the spacecraft will unfurl a tennis-court-size sunshield that will block light and heat from the Sun, Earth, and Moon using five layers of specially coated material. Each layer blocks incoming heat, and the heat that does make it through is redirected out of the sides of the sunshield. Additionally, the vacuum between each layer provides insulation.

Technicians in white smocks stand on lifts looking at JWST's fully deployed sunshield in the cleanroom at Northrup Gruman. The five layers of the kite-shaped sunshield extend out around JWST's folded honeycomb-shaped mirror.

The sunshield is made up of five layers of specially coated material designed to block the Webb telescope's sensitive instruments from incoming heat from the Sun, Earth, and Moon. This photo, taken in the cleanroom at Northrop Grumman in Southern California in December 2020, shows the sunshield fully deployed and tensioned as it will be in space. Credit: NASA/Chris Gunn | › Full image and caption | + Expand image

The sunshield is so effective that the temperatures on the Sun-facing side of the telescope could be hot enough to boil water, while on the side closest to the instruments, the temperature could be as low as -394 F (-237 C, 36 K).

That’s cold enough for the near-infrared instruments to operate, but the Mid-Infrared Instrument, or MIRI, needs to be even colder. To bring down the temperature of MIRI, the Webb telescope is equipped with a special cryocooler that pumps chilled helium to the instrument to reduce its operating temperature to about -448 F (-267 C, 6 K).

Spotting Exoplanets

The Webb telescope will search for exoplanets using two different methods.

Using the transit method, the Webb telescope will look for the regular pattern of dimming that occurs when an exoplanet transits its star, or passes between the star and the telescope. The amount of dimming can tell scientists a lot about the passing exoplanet, such as the size of the planet and its distance from the star.

This animation shows how the transit method is used to hunt for planets outside our solar system. When exoplanets transit their parent star, the Webb telescope (like the Kepler space telescope, depicted here) will be able to detect the dip in the star’s brightness, providing scientists with key information about the transiting exoplanet. Students can see this technique in action with this transit math problem. Credit: NASA/JPL-Caltech | + Expand image

The second method the Webb telescope will use to search for exoplanets is direct imaging – capturing actual images of planets beyond our solar system. To enable direct imaging of exoplanets, the Webb telescope is equipped with a coronagraph. Just like you might use your hand to block a bright light, a coronagraph blocks starlight from reaching a telescope’s instruments, allowing a dim exoplanet orbiting a star to be seen.

Wispy solar flares from the Sun can be seen jutting out from a solid central circle.

This “coronagraph” image taken by the Solar and Heliospheric Observatory, or SOHO, shows dim features around our Sun. Similarly, direct images of exoplanets captured by the Webb telescope will reveal details normally washed out by the brightness of stars. Credit: ESA&NASA/SOHO | › Full image and caption | + Expand image

The Webb telescope can uncover even more using spectroscopy. Light from a star produces a spectrum, which displays the intensity of light at different wavelengths. When a planet transits its star, some of the light from the star will pass through the planet's atmosphere before reaching the Webb telescope. Since all elements and molecules, such as methane and water, absorb energy at specific wavelengths, spectra from light that has passed through a planet’s atmosphere may contain dark lines known as absorption lines that tell scientists if there are certain elements present.

This infographic shows the electromagnetic spectrum and how various wavelengths are used for different applications, such as infrared for remote controls.

By looking at the unique spectrum produced when the light from a star shines through the atmosphere of a transiting exoplanet, scientists can learn whether certain elements are present on that planet. Credit: NASA | + Expand image

Using direct imaging and spectroscopy, scientists can learn even more about an exoplanet, including its color, seasons, rotation, weather, and vegetation if it exists.

All this could lead scientists to the ultimate exoplanet discovery: an Earth-size planet with an atmosphere like ours in its star’s habitable zone – a place where liquid water could exist.

Setting Up in Space

The Webb telescope will launch from French Guiana on top of an Ariane 5 rocket, a massive rocket capable of lifting the telescope, which weighs nearly 14,000 pounds (6,200 kilograms), to its destination.

The telescope's large mirror and giant sunshield are too big to fit inside the 18-foot (5.4-meter) wide rocket fairing, which protects the spacecraft during launch. To overcome this challenge, engineers designed the telescope's mirror and sunshield to fold for launch.

Two sides of the mirror assembly fold back for launch, allowing them to fit inside the fairing. The sunshield, which is 69.5 feet (21 meters) long and 46.5 feet (14 meters) wide, is carefully folded 12 times like origami so that it's narrow enough for launch. These are just two examples of several folding mechanisms needed to fit the massive telescope in its rocket for launch.

It will take about a month for the Webb telescope to reach its destination and unfurl its mirrors and sunshield. Scientists need another five months to cool down the instruments to their operating temperatures and align the mirrors correctly.

Approximately six months after launch, checkouts should be complete, and the telescope will begin its first science campaign and science operations.

Learn more and follow along with the mission from launch and unfolding to science observations and discovery announcements on the James Webb Space Telescope website.

Teach It

Check out these resources to bring the real-life STEM behind the mission into your teaching with lesson guides for educators, projects and slideshows for students, and more.

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NASA's Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

TAGS: JWST, James Webb Space Telescope, electromagnetic spectrum, exoplanets, universe, solar system, big bang, cosmology, astronomy, star formation, galaxy, galaxies, telescope, life, technology, MIRI, Mars, Engineering, Teaching, Education, Classroom, Science

  • Lyle Tavernier
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