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Illustration of spacecraft on a light purple background that reads "NASA Pi Day Challenge"

Update: March 16, 2020 – The answers to the 2020 NASA Pi Day Challenge are here! View the illustrated answer key (also available as a text-only doc).


In the News

Our annual opportunity to indulge in a shared love of space exploration, mathematics and sweet treats has come around again! Pi Day is the March 14 holiday that celebrates the mathematical constant pi – the number that results from dividing any circle's circumference by its diameter.

Infographic of all of the Pi in the Sky 7 graphics and problems

Visit the Pi in the Sky 7 lesson page to explore classroom resources and downloads for the 2019 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech | + Expand image

Overhead view of Mars with a comparison of the smaller landing ellipse made possible by Range Trigger technology

A new Mars landing technique called Range Trigger is reducing the size of the ellipse where spacecraft touch down. Image credit: NASA/JPL-Caltech | › Full image and caption

Composite image of the Kuiper Belt object Arrokoth from NASA's New Horizons spacecraft. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko | › Full image and caption

Diagram of an airplane flying over a section of ocean with an example of the spectral data that CORAL collects

The CORAL mission records the spectra of light reflected from the ocean to study the composition and health of Earth's coral reefs. Image credit: NASA | + Expand image

Rays of bright orange and red shoot out diagonally from a blue circle surrounding the star Beta Pictoris

The star Beta Pictoris and its surrounding debris disk in near-infrared light. Image credit: ESO/A.-M. Lagrange et al. | › Full image and caption

Besides providing an excuse to eat all varieties of pie, Pi Day gives us a chance to appreciate some of the ways NASA uses pi to explore the solar system and beyond. You can do the math for yourself – or get students doing it – by taking part in the NASA Pi Day Challenge. Find out below how to test your pi skills with real-world problems faced by NASA space explorers, plus get lessons and resources for educators.

How It Works

The ratio of any circle's circumference to its diameter is equal to pi, which is often rounded to 3.14. But pi is what is known as an irrational number, so its decimal representation never ends, and it never repeats. Though it has been calculated to trillions of digits, we use far fewer at NASA.

Pi is useful for all sorts of things, like calculating the circumference and area of circular objects and the volume of cylinders. That's helpful information for everyone from farmers irrigating crops to tire manufacturers to soup-makers filling their cans. At NASA, we use pi to calculate the densities of planets, point space telescopes at distant stars and galaxies, steer rovers on the Red Planet, put spacecraft into orbit and so much more! With so many practical applications, it's no wonder so many people love pi!

In the U.S., 3.14 is also how we refer to March 14, which is why we celebrate the mathematical marvel that is pi on that date each year. 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.

The NASA Pi Day Challenge

This year's NASA Pi Day Challenge poses four puzzlers that require pi to compare the sizes of Mars landing areas, calculate the length of a year for one of the most distant objects in the solar system, measure the depth of the ocean from an airplane, and determine the diameter of a distant debris disk. Learn more about the science and engineering behind the problems below or click the link to jump right into the challenge.

› Take the NASA Pi Day Challenge
› Educators, get the lesson here!

Mars Maneuver

Long before a Mars rover touches down on the Red Planet, scientists and engineers must determine where to land. Rather than choosing a specific landing spot, NASA selects an area known as a landing ellipse. A Mars rover could land anywhere within this ellipse. Choosing where the landing ellipse is located requires compromising between getting as close as possible to interesting science targets and avoiding hazards like steep slopes and large boulders, which could quickly bring a mission to its end. In the Mars Maneuver problem, students use pi to see how new technologies have reduced the size of landing ellipses from one Mars rover mission to the next.

Cold Case

In January 2019, NASA's New Horizons spacecraft sped past Arrokoth, a frigid, primitive object that orbits within the Kuiper Belt, a doughnut-shaped ring of icy bodies beyond the orbit of Neptune. Arrokoth is the most distant Kuiper Belt object to be visited by a spacecraft and only the second object in the region to have been explored up close. To get New Horizons to Arrokoth, mission navigators needed to know the orbital properties of the object, such as its speed, distance from the Sun, and the tilt and shape of its orbit. This information is also important for scientists studying the object. In the Cold Case problem, students can use pi to determine how long it takes the distant object to make one trip around the Sun.

Coral Calculus

Coral reefs provide food and shelter to many ocean species and protect coastal communities against extreme weather events. Ocean warming, invasive species, pollutants, and acidification caused by climate change can harm the tiny living coral organisms responsible for building coral reefs. To better understand the health of Earth's coral reefs, NASA's COral Reef Airborne Laboratory, or CORAL, mission maps them from the air using spectroscopy, studying how light interacts with the reefs. To make accurate maps, CORAL must be able to differentiate among coral, algae and sand on the ocean floor from an airplane. And to do that, it needs to calculate the depth of the ocean at every point it maps by measuring how much sunlight passes through the ocean and is reflected upward from the ocean floor. In Coral Calculus, students use pi to measure the water depth of an area mapped by the CORAL mission and help scientists better understand the status of Earth's coral reefs.

Planet Pinpointer

Our galaxy contains billions of stars, many of which are likely home to exoplanets – planets outside our solar system. So how do scientists decide where to look for these worlds? Using data gathered by NASA's Spitzer Space Telescope, researchers found that they're more likely to find giant exoplanets around young stars surrounded by debris disks, which are made up of material similar to what's found in the asteroid belt and Kuiper Belt in our solar system. Sure enough, after discovering a debris disk around the star Beta Pictoris, researchers later confirmed that it is home to at least two giant exoplanets. Learning more about Beta Pictoris' debris disk could give scientists insight into the formation of these giant worlds. In Planet Pinpointer, put yourself in the role of a NASA scientist to learn more about Beta Pictoris' debris disk, using pi to calculate the distance across it.

Participate

Join the conversation and share your Pi Day Challenge answers with @NASAJPL_Edu on social media using the hashtag #NASAPiDayChallenge

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TAGS: K-12 Education, Math, Pi Day, Pi, NASA Pi Day Challenge, Events, Space, Educators, Teachers, Parents, Students, STEM, Lessons, Problem Set, Mars 2020, Perseverance, Curiosity, Mars rovers, Mars landing, MU69, Arrokoth, New Horizons, Earth science, Climate change, CORAL, NASA Expeditions, coral reefs, oceans, Spitzer, exoplanets, Beta Pictoris, stars, universe, space telescope

  • Lyle Tavernier
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In the News

On Jan. 30, 2020, the venerable Spitzer Space Telescope mission will officially come to an end as NASA makes way for a next-generation observatory. For more than 16 years, Spitzer has served as one of NASA’s four Great Observatories, surveying the sky in infrared. During its lifetime, Spitzer detected planets and signs of habitability beyond our solar system, returned stunning images of regions where stars are born, spied light from distant galaxies formed when the universe was young, and discovered a huge, previously-unseen ring around Saturn. Read on to learn more about this amazing mission and gather tools to teach your students that there truly is more than meets the eye in the infrared universe!

How It Worked

Human eyes can see only the portion of the electromagnetic spectrum known as visible light. This is because the human retina can detect only certain wavelengths of light through special photoreceptors called rods and cones. Everything we see with our eyes either emits or reflects visible light. But visible light is just a small portion of the electromagnetic spectrum. To "see" things that emit or reflect other wavelengths of light, we must rely on technology designed to sense those portions of the electromagnetic spectrum. Using this specialized technology allows us to peer into space and observe objects and processes we wouldn’t otherwise be able to see.

Infographic showing the electromagnetic spectrum and applications for various wavelengths.

This diagram shows wavelengths of light on the electromagnetic spectrum and how they're used for various applications. Image credit: NASA | + Expand image

Infrared is one of the wavelengths of light that cannot be seen by human eyes. (It can sometimes be felt by our skin as heat if we are close enough to a strong source.) All objects that have temperature emit many wavelengths of light. The warmer they are, the more light they emit. Most things in the universe are warm enough to emit infrared radiation, and that light can be seen by an infrared-detecting telescope. Because Earth’s atmosphere absorbs most infrared radiation, infrared observations of space are best conducted from outside the planet's atmosphere.

Learn more about the infrared portion of the electromagnetic spectrum and how NASA uses it to explore space. Credit: NASA/JPL-Caltech | Watch on YouTube

So, to get a look at space objects that were otherwise hidden from view, NASA launched the Spitzer Space Telescope in 2003. Cooled by liquid helium and capable of viewing the sky in infrared, Spitzer launched into an Earth-trailing orbit around the Sun, where it became part of the agency's Great Observatory program along with the visible-light and near-infrared-detecting Hubble Space Telescope, Compton Gamma-Ray Observatory and Chandra X-ray Observatory. (Keeping the telescope cold reduces the chances of heat, or infrared light, from the spacecraft interfering with its astronomical observations.)

Over its lifetime, Spitzer has been used to detect light from objects and regions in space where the human eye and optical, or visible-light-sensing, telescopes may see nothing.

Why It's Important

NASA's Spitzer Space Telescope has returned volumes of data, yielding numerous scientific discoveries.

Vast, dense clouds of dust and gas block our view of many regions of the universe. Infrared light can penetrate these clouds, enabling Spitzer to peer into otherwise hidden regions of star formation, newly forming planetary systems and the centers of galaxies.

A whisp of orange and green dust bows out beside a large blue star among a field of smaller blue stars.

The bow shock, or shock wave, in front of the giant star Zeta Ophiuchi shown in this image from Spitzer is visible only in infrared light. The bow shock is created by winds that flow from the star, making ripples in the surrounding dust. Image credit: NASA/JPL-Caltech | › Full image and caption

Infrared astronomy also reveals information about cooler objects in space, such as smaller stars too dim to be detected by their visible light, planets beyond our solar system (called exoplanets) and giant molecular clouds where new stars are born. Additionally, many molecules in space, including organic molecules thought to be key to life's formation, have unique spectral signatures in the infrared. Spitzer has been able to detect those molecules when other instruments have not.

Bursts of reds, oranges, greens, blues and violets spread out in all directions from a bright center source. Reds and oranges dominate the left side of the image.

Both NASA's Spitzer and Hubble space telescopes contributed to this vibrant image of the Orion nebula. Spitzer's infrared view exposed carbon-rich molecules, shown in this image as wisps of red and orange. Image credit: NASA/JPL-Caltech/T. Megeath (University of Toledo) & M. Robberto (STScI) | › Full image and caption

Stars are born from condensing clouds of dust and gas. These newly formed stars are optically visible only once they have blown away the cocoon of dust and gas in which they were born. But Spitzer has been able to see infant stars as they form within their gas and dust clouds, helping us learn more about the life cycles of stars and the formation of solar systems.

A blanket of green- and orange-colored stellar dust surrounds a grouping of purple, blue and red stars.

Newborn stars peek out from beneath their natal blanket of dust in this dynamic image of the Rho Ophiuchi dark cloud from Spitzer. The colors in this image reflect the relative temperatures and evolutionary states of the various stars. The youngest stars are shown as red while more evolved stars are shown as blue. Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA | › Full image and caption

Infrared emissions from most galaxies come primarily from stars as well as interstellar gas and dust. With Spitzer, astronomers have been able to see which galaxies are furiously forming stars, locate the regions within them where stars are born and pinpoint the cause of the stellar baby boom. Spitzer has given astronomers valuable insights into the structure of our own Milky Way galaxy by revealing where all the new stars are forming.

A bright band of crimson-colored dust stretches across the center of this image covered in tiny specs of light from hundreds of thousands of stars.

This Spitzer image, which covers a horizontal span of 890 light-years, shows hundreds of thousands of stars crowded into the swirling core of our spiral Milky Way galaxy. In visible-light pictures, this region cannot be seen at all because dust lying between Earth and the galactic center blocks our view. Image credit: NASA/JPL-Caltech | › Full image and caption

Spitzer marked a new age in the study of planets outside our solar system by being the first telescope to directly detect light emitted by these so-called exoplanets. This has made it possible for us to directly study and compare these exoplanets. Using Spitzer, astronomers have been able to measure temperatures, winds and the atmospheric composition of exoplanets – and to better understand their potential habitability. The discoveries have even inspired artists at NASA to envision what it might be like to visit these planets.

Collage of exoplanet posters from NASA

Thanks to Spitzer, scientists are learning more and more about planets beyond our solar system. These discoveries have even inspired a series of posters created by artists at NASA, who imagined what future explorers might encounter on these faraway worlds. Image credit: NASA/JPL-Caltech | › Download posters

Data collected by Spitzer will continue to be analyzed for decades to come and is sure to yield even more scientific findings. It's certainly not the end of NASA's quest to get an infrared window into our stellar surroundings. In the coming years, the agency plans to launch its James Webb Space Telescope, with a mirror more than seven times the diameter of Spitzer's, to see the universe in even more detail. And NASA's Wide Field Infrared Survey Telescope, or WFIRST, will continue infrared observations in space with improved technology. Stay tuned for even more exciting infrared imagery, discoveries and learning!

Teach It

Use these lessons, videos and online interactive features to teach students how we use various wavelengths of light, including infrared, to learn about our universe:


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Also, check out these related resources for kids from NASA’s Space Place:

TAGS: Teachable Moments, science, astronomy, K-12 education, teachers, educators, parents, STEM, lessons, activities, Spitzer, Space Telescope, Missions, Spacecraft, Stars, Galaxies, Universe, Infrared, Wavelengths, Spectrum, Light

  • Ota Lutz
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Collage of images and illustrations of planets, spacecraft and space objects

Whether discovering something about our own planet or phenomena billions of miles away, NASA missions and scientists unveiled a vast universe of mysteries this past decade. And with each daring landing, visit to a new world and journey into the unknown came new opportunities to inspire the next generation of explorers. Read on for a look at some of NASA's most teachable moments of the decade from missions studying Earth, the solar system and beyond. Plus, find out what's next in space exploration and how to continue engaging students into the 2020s with related lessons, activities and resources.

1. Earth's Changing Climate

Flat map of Earth with an animation of co2 data overlayed

Rising sea levels, shrinking ice caps, higher temperatures and extreme weather continued to impact our lives this past decade, making studying Earth’s changing climate more important than ever. During the 2010s, NASA and National Oceanic and Atmospheric Administration, or NOAA, led the way by adding new Earth-monitoring satellites to their fleets to measure soil moisture and study carbon dioxide levels. Meanwhile, satellites such as Terra and Aqua continued their work monitoring various aspects of the Earth system such as land cover, the atmosphere, wildfires, water, clouds and ice. NASA's airborne missions, such as Operation IceBridge, Airborne Snow Observatory and Oceans Melting Greenland, returned data on water movement, providing decision makers with more accurate data than ever before. But there's still more to be done in the future to understand the complex systems that make up Earth's climate and improve the scientific models that will help the world prepare for a warmer future. Using these missions and the science they're gathering as a jumping-off point, students can learn about the water cycle, build data-based scientific models and develop an understanding of Earth's energy systems.

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2. Teachable Moments in the Sky

Animated image of the Moon during a lunar eclipse

Astronomical events are a sure-fire way to engage students, and this past decade delivered with exciting solar and lunar eclipses that provided real-world lessons about the Sun, the Moon and lunar exploration. The total solar eclipse that crossed the U.S. in 2017 gave students a chance to learn about the dynamic interactions between the Sun and Moon, while brilliant lunar eclipses year after year provided students with lessons in lunar science. There's more to look forward to in the decade ahead as another solar eclipse comes to the U.S. in 2024 – one of nine total solar eclipses around the world in the 2020s. There will be 10 total lunar eclipses in the 2020s, but observing the Moon at any time provides a great opportunity to study celestial patterns and inspire future explorers. Using the lessons below, students can develop and study models to understand the size and scale of the Earth-Moon system, predict future Moon phases and engage in engineering challenges to solve problems that will be faced by future explorers on the Moon!

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3. Missions to Mars

Animation of Curiosity driving on Mars

The past decade showed us the Red Planet in a whole new light. We discovered evidence that suggests Mars could have once supported ancient life, and we developed a better understanding of how the planet lost much of its atmosphere and surface water. The Opportunity rover continued exploring long past its expected lifespan of 90 days as NASA sent a larger, more technologically advanced rover, Curiosity, to take the next steps in understanding the planet's ability to support life. (Opportunity's nearly 15-year mission succumbed to the elements in 2019 after a global dust storm engulfed Mars, blocking the critical sunlight the rover needed to stay powered.) The InSight lander touched down in 2018 to begin exploring interior features of the Red Planet, including marsquakes, while high above, long-lived spacecraft like the Mars Reconnaissance Orbiter and Mars Odyssey were joined by NASA's MAVEN Orbiter, and missions from the European Space Agency and the Indian Space Research Organization. The next decade on Mars will get a kick-start with the July launch of the souped-up Mars 2020 rover, which will look for signs of ancient life and begin collecting samples designed to one day be returned to Earth. Mars provides students with countless opportunities to do some of the same engineering as the folks at NASA and design ideas for future Mars exploration. They can also use Mars as a basis for coding activities, real-world math, and lessons in biology and geology.

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4. Ocean Worlds and the Search for Life

Image of Saturn's moon Enceladus covered in ice with giant cracks scarring its surface

This decade marked the final half of the Cassini spacecraft's 13-year mission at Saturn, during which it made countless discoveries about the planet, its rings and its fascinating moons. Some of the most exciting findings highlighted new frontiers in our search for life beyond Earth. Cassini spotted geysers erupting from cracks in the icy shell of Saturn's moon Enceladus, suggesting the presence of an ocean below. At the moon Titan, the spacecraft peered through the hazy atmosphere to discover an Earth-like hydrologic cycle in which liquid methane and ethane take the place of water. Meanwhile, evidence for another ocean world came to light when the Hubble Space Telescope spotted what appear to be geysers erupting from the icy shell surrounding Jupiter's moon Europa. NASA is currently developing Europa Clipper, a mission that will explore the icy moon of Jupiter to reveal even more about the fascinating world. For students, these discoveries and the moons themselves provide opportunities to build scientific models and improve them as they learn more information. Students can also use math to calculate physical properties of moons throughout the solar system and identify the characteristics that define life as we know it.

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5. Asteroids, Comets and Dwarf Planets, Oh My!

Animated image series of comet 67P/Churyumov-Gerasimenko in which the comet tail can be seen shooting out from the comet as it rotates slightly from the perspective of the Rosetta spacecraft

The past decade was a big deal for small objects in space. NASA's Dawn mission started 2010 as a new arrival in the main asteroid belt. The next eight years saw Dawn explore the two largest objects in the asteroid belt, the giant asteroid Vesta and the dwarf planet Ceres. On its way to comet 67P/Churyumov-Gerasimenko, ESA's Rosetta mission (with contributions from NASA) flew by the asteroid Luticia in 2010. After more than two years at its destination – during which time it measured comet properties, captured breathtaking photos and deposited a lander on the comet – Rosetta's mission ended in dramatic fashion in 2016 when it touched down on 67P/Churyumov-Gerasimenko. In 2013, as scientists around the world eagerly anticipated the near-Earth flyby of asteroid Duende, residents of Chelyabinsk, Russia, got a surprising mid-morning wake-up call when a small, previously undetected asteroid entered the atmosphere, burned as a bright fireball and disintegrated. The team from NASA's OSIRIS-Rex mission wrapped up the decade and set the stage for discoveries in 2020 by selecting the site that the spacecraft will visit in the new year to collect a sample of asteroid Bennu for eventual return to Earth. And in 2022, NASA's Psyche mission will launch for a rendezvous with a type of object never before explored up close: a metal asteroid. The small objects in our solar system present students with chances to explore the composition of comets, use math to calculate properties such as volume, density and kinetic energy of asteroids, and use Newton's Laws in real-world applications, such as spacecraft acceleration.

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6. Uncovering Pluto's Mysteries

Image of Pluto in false color from NASA's New Horizons mission

In 2015, after nearly a decade of travel, NASA's New Horizons spacecraft arrived at Pluto for its planned flyby and became the first spacecraft to visit the dwarf planet and its moons. The images and scientific data the spacecraft returned brought into focus a complex and dynamic world, including seas of ice and mountain ranges. And there's still more left to explore. But New Horizons' journey is far from over. After its flyby of Pluto, the spacecraft continued deep into the Kuiper Belt, the band of icy bodies beyond the orbit of Neptune. In 2019, the spacecraft flew by a snowman-shaped object later named Arrokoth. In the 2020s, New Horizons will continue studying distant Kuiper Belt objects to better understand their physical properties and the region they call home. The new information gathered from the Pluto and Arrokoth flybys provides students with real-life examples of the ways in which scientific understanding changes as additional data is collected and gives them a chance to engage with the data themselves. At the same time, New Horizons' long-distance voyage through the Solar System serves as a good launchpad for discussions of solar system size and scale.

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7. The Voyagers' Journey Into Interstellar Space

Animation of Voyager entering interstellar space

In 1977, two spacecraft left Earth on a journey to explore the outer planets. In the 2010s, decades after their prime mission ended, Voyager 1 and Voyager 2 made history by becoming the first spacecraft to enter interstellar space – the region beyond the influence of solar wind from our Sun. The Voyager spacecraft are expected to continue operating into the 2020s, until their fuel and power run out. In the meantime, they will continue sending data back to Earth, shaping our understanding of the structure of the solar system and interstellar space. The Voyagers can help engage students as they learn about and model the structure of the solar system and use math to understand the challenges of communicating with spacecraft so far away.

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8. The Search for Planets Beyond Our Solar System

Illustration of the TRAPPIST-1 star and its system of planets

It was only a few decades ago that the first planets outside our solar system, or exoplanets, were discovered. The 2010s saw the number of known exoplanets skyrocket in large part thanks to the Kepler mission. A space telescope designed to seek out Earth-sized planets orbiting in the habitable zone – the region around a star where liquid water could exist – Kepler was used to discover more than 2,600 exoplanets. Discoveries from other observatories and amateur astronomers added to the count, now at more than 4,100. In one of the most momentous exoplanet findings of the decade, the Spitzer telescope discovered that the TRAPPIST-1 system, first thought to have three exoplanets, actually had seven – three of which were in the star’s habitable zone. With thousands of candidates discovered by Kepler waiting to be confirmed as exoplanets and NASA's latest space telescope, the Transiting Exoplanet Survey Satellite, or TESS, surveying the entire sky, the 2020s promise to be a decade filled with exoplanet science. And we may not have to wait long for exciting new discoveries from the James Webb Space Telescope, set to launch in 2021. Exoplanets are a great way to get students exploring concepts in science and mathematics. In the lessons linked to below, students use math to find the size and orbital period of planets, learn how scientists are using spectrometry to determine what makes up exoplanet atmospheres and more.

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9. Shining a Light on Black Holes

In this historic first image of a black hole, an orange glowing donut-shaped light can be seen against the black backdrop of space. At the center of the light is a black hole.

Even from millions and billions of light-years away, black holes made big news in the 2010s. First, a collision of two black holes 1.3 billion light-years away sent gravitational waves across the universe that finally reached Earth in 2015, where the waves were detected by the Laser Interferometer Gravitational-Wave Observatory, or LIGO. This was the first detection of gravitational waves in history and confirmed a prediction Einstein made 100 years earlier in his Theory of General Relativity. Then, in 2019, a team of researchers working on the Event Horizon Telescope project announced they had taken the first image capturing the silhouette of a black hole. To take the historic image of the supermassive black hole (named M87* after its location at the center of the M87 galaxy), the team had to create a virtual telescope as large as Earth itself. In addition to capturing the world's attention, the image gave scientists new information about scientific concepts and measurements they had only been able to theorize about in the past. The innovations that led to these discoveries are changing the way scientists can study black holes and how they interact with the space around them. More revelations are likely in the years ahead as scientists continue to analyze the data from these projects. For students, black holes and gravitational waves provide a basis for developing and modifying scientific models. Since they are a topic of immense interest to students, they can also be used to encourage independent research.

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TAGS: Teachable Moments, K-12 Education, Educators, Students, STEM, Lessons, Activities, Climate, Moon, Mars, Ocean Worlds, Small Objects, Pluto, Voyager, Exoplanets, Black Holes

  • Lyle Tavernier
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Animated image of Mercury passing in front of the Sun during the 2019 transit of Mercury

In the News

It only happens about 13 times a century and won’t happen again until 2032, so don’t miss the transit of Mercury on Monday, Nov. 11! A transit happens when a planet crosses in front of a star. From our perspective on Earth, we only ever see two planets transit the Sun: Mercury and Venus. This is because these are the only planets between us and the Sun. (Transits of Venus are especially rare. The next one won’t happen until 2117.) During the upcoming transit of Mercury, viewers around Earth (using the proper safety equipment) will be able to see a tiny dark spot moving slowly across the disk of the Sun.

Read on to learn how transits contributed to past scientific discoveries and for a look at how scientists use them today. Plus, find resources for engaging students in this rare celestial event!

Why It's Important

Then and Now

In the early 1600s, Johannes Kepler discovered that both Mercury and Venus would transit the Sun in 1631. It was fortunate timing: The telescope had been invented just 23 years earlier, and the transits of both planets wouldn’t happen in the same year again until 13425. Kepler didn’t survive to see the transits, but French astronomer Pierre Gassendi became the first person to see the transit of Mercury. Poor weather kept other astronomers in Europe from seeing it. (Gassendi attempted to view the transit of Venus the following month, but inaccurate astronomical data led him to mistakenly believe it would be visible from his location.) It was soon understood that transits could be used as an opportunity to measure apparent diameter – how large a planet appears from Earth – with great accuracy.

After observing the transit of Mercury in 1677, Edmond Halley predicted that transits could be used to accurately measure the distance between the Sun and Earth, which wasn’t known at the time. This could be done by having observers at distant points on Earth look at the variation in a planet’s apparent position against the disk of the Sun – a phenomenon known as parallax shift. This phenomenon is what makes nearby objects appear to shift more than distant objects when you look out the window of a car, for example.

Today, radar is used to measure the distance between Earth and the Sun with greater precision than transit observations. But the transits of Mercury and Venus still provide scientists with opportunities for scientific investigation in two important areas: exospheres and exoplanets.

Exosphere Science

Some objects, like the Moon and Mercury, were originally thought to have no atmosphere. But scientists have discovered that these bodies are actually surrounded by an ultrathin atmosphere of gases called an exosphere. Scientists want to better understand the composition and density of the gases in Mercury’s exosphere, and transits make that possible.

“When Mercury is in front of the Sun, we can study the exosphere close to the planet,” said NASA scientist Rosemary Killen. “Sodium in the exosphere absorbs and re-emits a yellow-orange color from sunlight, and by measuring that absorption, we can learn about the density of gas there.”

Exoplanet Discoveries

When Mercury transits the Sun, it causes a slight dip in the Sun’s brightness as it blocks a tiny portion of the Sun’s light. Scientists discovered they could use that phenomenon to search for planets orbiting distant stars. These planets, called exoplanets, are otherwise obscured from view by the light of their star. When measuring the brightness of far-off stars, a slight recurring dip in the light curve (a graph of light intensity) could indicate an exoplanet orbiting and transiting its star. NASA’s Kepler space telescope found more than 2,700 exoplanets by looking for this telltale drop in brightness. NASA’s TESS mission is surveying 200,000 of the brightest stars near our solar system and is expected to potentially discover more than 10,000 transiting exoplanets.

Animated cartoon image of a planet crossing in front of a star and an inset that shows a graph dipping as the planet does so

This animation shows one method scientists use to hunt for planets outside our solar system. When exoplanets transit their parent star, we can detect the dip in the star’s brightness using space telescopes. Credit: NASA/JPL-Caltech | + Expand image

Additionally, scientists have been exploring the atmospheres of exoplanets. Similarly to how we study Mercury’s exosphere, scientists can observe the spectra – a measure of light intensity and wavelength – that passes through an exoplanet’s atmosphere. As a result, they’re beginning to understand the evolution and composition of exoplanet atmospheres, as well as the influence of stellar wind and magnetic fields.

Collage of exoplanet posters from NASA

Using the transit method and other techniques, scientists are learning more and more about planets beyond our solar system. These discoveries have even inspired a series of posters created by artists at NASA, who imagine what future explorers might encounter on these faraway worlds. Credit: NASA | › Download posters

Watch It

During the transit of Mercury, the planet will appear as a tiny dot on the Sun’s surface. To see it, you’ll need a telescope or binoculars outfitted with a special solar filter.

WARNING! Looking at the Sun directly or through a telescope without proper protection can lead to serious and permanent vision damage. Do not look directly at the Sun without a certified solar filter.

The transit of Mercury will be partly or fully visible across much of the globe. However, it won’t be visible from Australia or most of Asia and Alaska.

Graphic showing Mercury's path across the Sun on Nov. 11, 2019 and the times that it will be at each location

The transit of Mercury on Nov. 11, 2019, begins at 4:35 a.m. PST (7:35 a.m. EST), but it won’t be visible to West Coast viewers until after sunrise. Luckily, viewers will have several more hours to take in the stellar show, which lasts until 10:04 a.m. PST (1:04 p.m. EST). Credit: NASA/JPL-Caltech | + Expand image

Mercury’s trek across the Sun begins at 4:35 a.m. PST (7:35 a.m. EST), meaning viewers on the East Coast of the U.S. can experience the entire event, as the Sun will have already risen before the transit begins. By the time the Sun rises on the West Coast, Mercury will have been transiting the Sun for nearly two hours. Fortunately, the planet will take almost 5.5 hours to completely cross the face of the Sun, so there will be plenty of time for West Coast viewers to witness this event. See the transit map below to learn when and where the transit will be visible.

Graphic showing a flat map of the world with areas where the transit of Mercury on Nov. 11, 2019 will be partially to fully visible indicated along with transit start and end times

This map shows where and when the transit will be visible on November 11. Image credit: NASA/JPL-Caltech | + Expand image

Don’t have access to a telescope or binoculars with a solar filter? Visit the Night Sky Network website to find events near you where amateur astronomers will have viewing opportunities available.

During the transit, NASA will share near-real-time images of the Sun directly from the Solar Dynamics Observatory. Beginning at 4:41 a.m. PST (7:41 a.m. EST) you can see images of Mercury passing in front of the Sun at NASA’s 2019 Mercury Transit page, with updates through the end of the transit at 10:04 a.m. PST (1:04 p.m. EST).

If you’re in the U.S., don’t miss the show, as this is the last time a transit will be visible from the continental United States until 2049!

Watch this month's installment of "What's Up" to learn more about how to watch the Nov. 11 transit of Mercury. Credit: NASA/JPL-Caltech | Watch on YouTube

Teach It

Use these lessons and activities to engage students in the transit of Mercury and the hunt for planets beyond our solar system:

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Transit Resources:

Exoplanet Resources:

Check out these related resources for kids from NASA’s Space Place:

TAGS: K-12 Education, Teachers, Students, Educators, Mercury, Transit, Transit of Mercury, What's Up, Astronomy, Resources for Educators, Exoplanets, Kepler, TESS

  • Lyle Tavernier
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Side-by-side satellite and data images of soil moisture, flooding, temperature, a snowstorm, a wildfire and a hurricane

In the News

An extreme weather event is something that falls outside the realm of normal weather patterns. It can range from superpowerful hurricanes to torrential downpours to extended hot dry weather and more. Extreme weather events are, themselves, troublesome, but the effects of such extremes, including damaging winds, floods, drought and wildfires, can be devastating.

NASA uses airborne and space-based platforms, in conjunction with those from the National Oceanic and Atmospheric Administration, or NOAA, to monitor these events and the ways in which our changing climate is contributing to them. Together, the agencies are collecting more detailed data on weather and climate than ever before, improving society's ability to predict, monitor and respond to extreme events.

NASA makes this data available to the public, and students can use it to understand extreme weather events happening in their regions, learn more about weather and climate in general, and design plans for resilience and mitigation. Read on for a look at the various kinds of extreme weather, how climate change is impacting them, and ways students can use NASA data to explore science for themselves.

How It Works

Global climate change, or the overall warming of our planet, has had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up and melting earlier in the year, precipitation patterns have changed, plant and animal habitat ranges have shifted, and trees are flowering sooner, exposing fruit blossoms to damaging erratic spring hail and deadly late frost. Effects that scientists had predicted in the past are now occurring: loss of sea ice, accelerated sea level rise, shifting storm patterns and longer, more intense heat waves.

Some of the most visible and disruptive effects of global climate change are extreme weather and resulting disasters such as wildfires and flooding. These events vary by geographic location, with many regions, such as the Southwest United States and parts of Central and South America, Asia, Europe, Africa and Australia, experiencing more heat, drought and insect outbreaks that contribute to increased wildfires. Other regions of the world, including coastal areas of the United States and many island nations, are experiencing flooding and salt water intrusion into drinking water wells as a result of sea level rise and storm surges from intense tropical storms. And some areas of the world, such as the Midwestern and Southern United States, have been inundated with rain that has resulted in catastrophic flooding.

Side-by-side images showing the river on a typical day and the river flooded

This pair of images shows the northeast side of Tulsa, Oklahoma, in May 2018 (left) and in May 2019 (right) after the Caney and Verdigris rivers flooded. Image credit: NASA/USGS | › Full image and caption

Temperatures, rainfall, droughts, high-intensity hurricanes and severe flooding events all are increasing and projected to continue as the world's climate warms, according to the National Climate Assessment. Weather is dynamic and various types of weather can interact to produce extreme outcomes. Here's how climate change can play a role in some of these weather extremes.

High Temperatures

This color-coded map displays a progression of changing global surface temperature anomalies from 1880 through 2018. Higher-than-normal temperatures are shown in red and lower-than-normal temperatures are shown in blue. The final frame represents the global temperatures five-year averaged from 2014 through 2018. Scale in degrees Celsius. Credit: NASA's Scientific Visualization Studio. Data provided by Robert B. Schmunk (NASA/GSFC GISS). | Watch on YouTube

Eighteen of the 19 warmest years on record have occurred since 2001. September 2019 tied as the hottest month on record for the planet. Since the 1880s, the average global surface temperature has risen about 2 degrees Fahrenheit (1 degree Celsius). As a result of warming temperatures, global average sea level has risen nearly 7 inches (178 millimeters) over the past 100 years. Data show this warming of the Earth system has been driven in large part by increased emissions into the atmosphere of carbon dioxide and other greenhouse gases created by human activities. And as temperatures continue to rise, we can expect more extreme weather.

Drought and Wildfires

Side-by-side images showing red areas throughout Alaska representing hotter than usual temperatures and a satellite image showing smoke and clouds coming from the same areas

The image on the left shows air temperatures during a record-breaking June 2019 heat wave in Alaska. Around the same time, a cluster of lightning-triggered wildfires broke out in the same area. Smoke from the wildfires can be seen in the image on the right. Image credit: NASA | › Full image and caption

High temperatures alone can lead to drought. Drought can cause problems for humans, animals and crops dependent on water and can weaken trees, making them more susceptible to disease and insect attacks. High temperatures combined with low humidity, dry vegetation and hot, dry, fast winds typify what is known as "fire weather" or "fire season." During fire season, wildfires are more likely to start, spread rapidly and be difficult to extinguish.

A satellite image of Northern California showing a dark reddish brown section with smoke eminating from it

The Operational Land Imager on the Landsat 8 satellite captured this image of the Walker Fire in Northern California on Sept. 8, 2019. Image credit: NASA/USGS | › Full image and caption

In California, where climate change has brought hotter, drier weather, residents are plagued by two fire seasons – one lasting from June through September that is primarily caused by high heat, low humidity and dry vegetation, and another lasting from October through April that is generally more volatile, as it is fueled by high winds. This 11-month fire season is longer than in past years. In recent years, California has also seen an increase in destructive wildfires. Weather extremes and climate change are partly to blame, even in relatively wet years. In California, these years mean more plant growth and potentially more fuel for fires when those plants dry out in the fall and the winds arrive. Wildfires have some fairly obvious effects on people and property. In addition to the visible destruction, smoke from wildfires can dramatically decrease air quality, pushing carbon into the air and destroying important carbon-sequestering plants and trees. Large-scale biomass destruction, as is happening in the Amazon rainforest, will have a lasting impact on important Earth processes.

Hurricanes

Satellite image of a hurricane heading towards Japan

This image, acquired on October 11, 2019, by the Moderate Resolution Imaging Spectroradiometer, or MODIS, on NASA's Aqua satellite, shows Typhoon Hagibis as its outer cloud bands neared Japan. Image credit: NASA | › Full image and caption

Since the 1980s, regions of the world prone to hurricanes, cyclones and typhoons have witnessed an increase in intensity, frequency and duration of these destructive storms. All three are intense tropical storms that form over oceans. (The different names refer to where on Earth they occur.) They are all fueled by available heat energy from warm ocean water. Warmer oceans provide more energy to passing storms, meaning hurricanes can form more quickly and reach higher speeds. Typhoon Hagibis, which recently left a trail of destruction in Japan, was described as the worst storm to hit the region in decades. Growing unusually quickly from a tropical storm to a Category 5 storm in less than a day, Hagibis was so intense it was called a super typhoon. In 2018, the second strongest cyclone to hit a U.S. territory and the largest typhoon of the year, Super Typhoon Yutu, caused catastrophic destruction on the Mariana Islands, an archipelago in the North Pacific Ocean. More intense storms and rising sea levels make storm surge – ocean water that is pushed toward the shore by strong winds – even worse than in the past. Typhoons can wreak havoc on infrastructure and compromise fresh water reserves. It can take months or even years for a hard-hit region to recover.

Snowstorms

Satellite image of white snow clouds and snow over the Mid-Alantic U.S.

The MODIS instrument aboard NASA's Terra Satellite captured the low-pressure area near New England that brought heavy snows and thundersnow to the Mid-Atlantic and Northeastern U.S. in January 2011. Image credit: NASA Goddard/MODIS Rapid Response Team | › Full image and caption

Like any other weather event, extreme cold weather events such as blizzards and unusually heavy snowfall can be, but are not always, linked to climate change. Just as warmer ocean water increases the intensity of a warm tropical storm, warmer than average winter ocean temperatures in the Atlantic feed additional energy and moisture into cold storms, influencing the severity of snowfall once the storm comes ashore in the Eastern United States. There is some natural variability, such as the presence of El Niño conditions, that can also lead to severe snowstorms in the region. But natural variability isn't enough to fully explain the increase in major snowstorms in the U.S. In fact, the frequency of extreme snowstorms in the eastern two-thirds of the region has increased dramatically over the last century. Approximately twice as many extreme snowstorms occurred in the U.S. during the latter half of the 20th century as in the first half.

Why It's Important

Because of the risk to lives and property, monitoring the increasing number of extreme weather events is more important now than ever before. And a number of NASA satellites and airborne science instruments are doing just that.

Artist's concept of dozens of satellites circling Earth with a glare from the Sun in the background

This graphic shows NASA's fleet of Earth-science satellites designed to monitor weather and climate across the globe. Image credit: NASA | › Full image and caption

A large global constellation of satellites, operated by NASA and NOAA, combined with a small fleet of planes operated by the U.S. Forest Service, help detect and map the extent, spread and impact of forest fires. As technology has advanced, so has the value of remote sensing, the science of scanning Earth from a distance using satellites and high-flying airplanes. Wildfire data from satellites and aircraft provide information that firefighters and command centers can use to call evacuation orders and make decisions about where to deploy crews to best arrest a fire's progress.

The agencies' satellites and airborne instruments also work in conjunction with those from international partners to provide data about hurricanes to decision makers at the National Hurricane Center, where predictions and warnings are issued so evacuations can be coordinated among the public and local authorities. Visible imagery from NASA satellites helps forecasters understand whether a storm is brewing or weakening based on changes to its structure. Other instruments on NASA satellites can measure sea surface characteristics, wind speeds, precipitation, and the height, thickness and inner structure of clouds.

Three side-by-side data images of the hurricane from different perspectives with colors overlayed to represent various science data

Three images of Hurricane Dorian, as seen by a trio of NASA's Earth-observing satellites in August 2019. The data sent by the spacecraft revealed in-depth views of the storm, including detailed heavy rain, cloud height and wind. Image credit: NASA/JPL-Caltech | › Full image and caption

NASA's airborne instruments, such as those aboard the Global Hawk aircraft, provide data from within the storm that cannot be otherwise obtained. Global Hawk can fly above a storm in a back-and-forth pattern and drop instruments called dropsondes through the storm. These instruments measure winds, temperature, pressure and humidity on their way to the surface. This detailed data can be used to characterize a storm, informing scientists of shifting patterns and potential future developments.

NASA missions will continue to study both weather and climate phenomena – whether they be droughts, floods, wildfires, hurricanes or other extremes – returning data for analysis. New airborne instruments aboard the satellite-simulating ER-2 and cloud-penetrating P-3 aircraft will fly missions starting in 2020 to study Atlantic coast-threatening snowstorms. Data from these flights will be combined with ground-based radar measurements and satellite measurements to better understand storms and their potential impact. Meanwhile, climate science instruments and satellites will continue to collect data that can inform everyone about the many aspects of our changing planet.

Teach It

Weather and climate data isn't just for meteorologists. Explore the resources and standards-aligned lessons below to get students analyzing local weather patterns, understanding wildfire monitoring and modeling global climate!

Precipitation and Clouds

Wildfires and Temperature

Sea Level

Satellites and Data

Climate

For Students

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Resources for Students

TAGS: Earth, Earth science, climate change, weather, extreme weather, hurricane, wildfire, typhoons, drought, flood, sea level rise

  • Ota Lutz
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Buzz Aldrin stands on the moon in his puffy, white spacesuit next to an American flag waving in the wind. The command module casts a long, dark shadow nearby.

In the News

This year marks the 50th anniversary of humans landing on the Moon. Now NASA is headed to the Moon once again, using it as a proving ground for a future human mission to Mars. Use this opportunity to get students excited about Earth's natural satellite, the amazing feats accomplished 50 years ago and plans for future exploration.

How They Did It

When NASA was founded in 1958, scientists were unsure whether the human body could even survive orbiting Earth. Space is a demanding environment. Depending on where in space you are, it can lack adequate air for breathing, be very cold or hot, and have dangerous levels of radiation. Additionally, the physics of space travel make everything inside a space capsule feel weightless even while it's hurtling through space. Floating around inside a protective spacecraft may sound fun, and it is, but it also can have detrimental effects on the human body. Plus, it can be dangerous with the hostile environment of space lurking on the other side of a thin metal shell.

In 1959, NASA's Jet Propulsion Laboratory began the Ranger project, a mission designed to impact the Moon – in other words, make a planned crash landing. During its descent, the spacecraft would take pictures that could be sent back to Earth and studied in detail. These days, aiming to merely impact a large solar system body sounds rudimentary. But back then, engineering capabilities and course-of-travel, or trajectory, mathematics were being developed for the first time. A successful impact would be a major scientific and mathematical accomplishment. In fact, it took until July 1964 to achieve the monumental task, with Ranger 7 becoming the first U.S. spacecraft to impact the near side of the Moon, capturing and returning images during its descent.

Side-by-side images of a model of the Ranger 7 spacecraft in color and a black and white image of the Moon taken by Ranger 7.

These side-by-side images show a model of the Ranger 7 spacecraft (left) and an image the spacecraft took of the Moon (right) before it impacted the surface. Image credit: NASA/JPL-Caltech | › + Expand image

After the successful Ranger 7 mission, two more Ranger missions were sent to the Moon. Then, it was time to land softly. For this task, JPL partnered with Hughes Aircraft Corporation to design and operate the Surveyor missions between 1966 and 1968. Each of the seven Surveyor landers were equipped with a television camera – with later landers carried scientific instruments, too – aimed at obtaining up-close lunar surface data to assess the Moon's suitability for a human landing. The Surveyors also demonstrated in-flight maneuvers and in-flight and surface-communications capabilities.

Side-by-side image of an astronaut next to the Surveyor 7 lander and a mosaic of images from Surveyor 3

These side-by-side images show Apollo 12 Commander Charles Conrad Jr. posing with the Surveyor 7 spacecraft on the Moon (left) and a mosaic of images taken by Surveyor 3 on the lunar surface (right). Image credits: NASA/JPL-Caltech | › + Expand image

In 1958, at the same time JPL was developing the technological capabilities to get to the Moon, NASA began the Mercury program to see if it was possible for humans to function in space. The success of the single-passenger Mercury missions, with six successful flights that placed two astronauts into suborbital flight and four astronauts into Earth orbit, kicked off the era of U.S. human spaceflight.

Cutaway illustration of the Mercury capsule with a single astronaut inside.

The success of the single-passenger Mercury capsule, shown in this illustrated diagram, proved that humans could live and work in space, paving the way for future human exploration. Image credit: NASA | › Full image and caption

In 1963, NASA's Gemini program proved that a larger capsule containing two humans could orbit Earth, allowing astronauts to work together to accomplish science in orbit for long-duration missions (up to two weeks in space) and laying the groundwork for a human mission to the Moon. With the Gemini program, scientists and engineers learned how spacecraft could rendezvous and dock while in orbit around Earth. They were also able to perfect re-entry and landing methods and began to better understand the effects of longer space flights on astronauts. After the successful Gemini missions, it was time to send humans to the Moon.

Cutaway illustration of the Gemini spacecraft with two astronauts inside.

The Gemini spacecraft, shown in this illustrated cutaway, paved the way for the Apollo missions. Image credit: NASA | › Full image and caption

The Apollo program officially began in 1963 after President John F. Kennedy directed NASA in September of 1962 to place humans on the Moon by the end of the decade. This was a formidable task as no hardware existed at the time that would accomplish the feat. NASA needed to build a giant rocket, a crew capsule and a lunar lander. And each component needed to function flawlessly.

Rapid progress was made, involving numerous NASA and contractor facilities and hundreds of thousands of workers. A crew capsule was designed, built and tested for spaceflight and landing in water by the NASA contractor North American Aviation, which eventually became part of Boeing. A lunar lander was developed by the Grumman Corporation. Though much of the astronaut training took place at or near the Manned Spacecraft Center, now known as NASA’s Johnson Space Center, in Texas, astronauts practiced lunar landings here on Earth using simulators at NASA's Dryden (now Armstrong) Flight Research Center in California and at NASA's Langley Research Center in Virginia. The enormous Saturn V rocket was a marvel of complexity. Its first stage was developed by NASA's Marshall Space Flight Center in Alabama. The upper-stage development was managed by the Lewis Flight Propulsion Center, now known as NASA's Glenn Research Center, in Ohio in partnership with North American Aviation and Douglas Aircraft Corporation, while Boeing integrated the whole vehicle. The engines were tested at what is now NASA's Stennis Space Center in Mississippi, and the rocket was transported in pieces by water for assembly at Cape Kennedy, now NASA's Kennedy Space Center, in Florida. As the Saturn V was being developed and tested, NASA also developed a smaller, interim vehicle known as the Saturn I and started using it to test Apollo hardware. A Saturn I first flew the Apollo command module design in 1964.

Unfortunately, one crewed test of the Apollo command module turned tragic in February 1967, when a fire erupted in the capsule and killed all three astronauts who had been designated as the prime crew for what became known as Apollo 1. The command module design was altered in response, delaying the first crewed Apollo launch by 21 months. In the meantime, NASA flew several uncrewed Apollo missions to test the Saturn V. The first crewed Apollo launch became Apollo 7, flown on a Saturn IB, and proved that the redesigned command module would support its crew while remaining in Earth orbit. Next, Earth-Moon trajectories were calculated for this large capsule, and the Saturn V powered Apollo 8 set off for the Moon, proving that the calculations were accurate, orbiting the Moon was feasible and a safe return to Earth was possible. Apollo 8 also provided the first TV broadcast from lunar orbit. The next few Apollo missions further proved the technology and allowed humans to practice procedures that would be needed for an eventual Moon landing.

On July 16, 1969, a Saturn V rocket launched three astronauts to the Moon on Apollo 11 from Cape Kennedy. The Apollo 11 spacecraft had three parts: a command module, called "Columbia," with a cabin for the three astronauts; a service module that provided propulsion, electricity, oxygen and water; and a lunar module, "Eagle," that provided descent to the lunar surface and ascent back to the command and service modules.

Collage of three images showing the lunar module during its descent to the Moon, on the lunar surface and during its ascent.

In this image collage, the Apollo 11 lunar module is shown on its descent to the Moon (left), on the lunar surface as Buzz Aldrin descends the stairs (middle), and on its ascent back to the command module (right). Image credit: NASA | › View full image collection

On July 20, while astronaut and command module pilot Michael Collins orbited the Moon, Neil Armstrong and Buzz Aldrin landed Eagle on the Moon and set foot on the surface, accomplishing a first for humankind. They collected regolith (surface "dirt") and rock samples, set up experiments, planted an American flag and left behind medallions honoring the Apollo 1 crew and a plaque that read, "We came in peace for all mankind."

Collage of images showing Buzz Aldrin doing various activities on the Moon.

This collage of images from the Apollo 11 Moon landing shows Buzz Aldrin posing for a photo on the Moon (left), and setting up the solar wind and seismic experiments (middle). The image on the right shows the plaque the team placed on Moon to commemorate the historic event. Image credit: NASA | › View full image collection

After 21.5 hours on the lunar surface, Armstrong and Aldrin rejoined Collins in the Columbia command module and, on July 21, headed back to Earth. On July 24, after jettisoning the service module, Columbia entered Earth's atmosphere. With its heat shield facing forward to protect the astronauts from the extreme friction heating outside the capsule, the craft slowed and a series of parachutes deployed. The module splashed down in the South Pacific Ocean, 380 kilometers (210 nautical miles) south of Johnston Atoll. Because scientists were uncertain about contamination from the Moon, the astronauts donned biological-isolation garments delivered by divers from the recovery ship, the aircraft carrier the USS Hornet. The astronauts boarded a life raft and then the USS Hornet, where the outside of their biological-isolation suits were washed down with disinfectant. To be sure no contamination was brought back to Earth from the Moon, the astronauts were quarantined until Aug. 10, at which point scientists determined the risk was low that biological contaminants or microbes had returned with the astronauts. Columbia was also disinfected and is now part of the National Air and Space Museum in Washington, D.C.

On the left, a capsule floats in the ocean while astronauts sit in a raft in a gray suits. On the right, the three astronauts smile while looking out of a small window and while Nixon faces them with a microphone in front of him.

These side-by-side images show the Apollo 11 astronauts leaving the capsule in their biological isolation garments after successfully splashing down in the South Pacific Ocean (left). At right, President Richard M. Nixon welcomes the Apollo 11 astronauts, (left to right) Neil A. Armstrong, Michael Collins and Buzz Aldrin, while they peer through the window of the Mobile Quarantine Facility aboard the USS Hornet. Image credit: NASA | › View full image collection

The Apollo program continued with six more missions to the Moon over the next three years. Astronauts placed seismometers to measure "moonquakes" and other science instruments on the lunar surface, performed science experiments, drove a carlike moon buggy on the surface, planted additional flags and returned more lunar samples to Earth for study.

Why It's Important

Apollo started out as a demonstration of America's technological, economic and political prowess, which it accomplished with the first Moon landing. But the Apollo missions accomplished even more in the realm of science and engineering.

Some of the earliest beneficiaries of Apollo research were Earth scientists. The Apollo 7 and 9 missions, which stayed in Earth orbit, took photographs of Earth in different wavelengths of light, highlighting things that might not be seen on the ground, like diseased trees and crops. This research led directly to the joint NASA-U.S. Geological Survey Landsat program, which has been studying Earth's resources from space for more than 45 years.

Samples returned from the Moon continue to be studied by scientists around the world. As new tools and techniques are developed, scientists can learn even more about our Moon, discovering clues to our planet's origins and the formation of the solar system. Additionally, educators can be certified to borrow lunar samples for use in their classrooms.

The Apollo 11 astronauts crowd around a lunar sample contained in a protective case.

The Apollo 11 astronauts take a closer look at a sample they brought back from the Moon. Image credit: NASA | › View full image collection

Perhaps the most important scientific finding came from comparing similarities in the composition of lunar and terrestrial rocks and then noting differences in the amount of specific substances. This suggested a new theory of the Moon's formation: that it accreted from debris ejected from Earth by a collision with a Mars-size object early in our planet's 4.5-billion-year history.

The 12 astronauts who walked on the Moon are the best-known faces of the Apollo program, but in numbers, they were also the smallest part of the program. About 400,000 men and women worked on Apollo, building the vehicles, calculating trajectories, even making and packing food for the crews. Many of them worked on solving a deceptively simple question: "How do we guide astronauts to the Moon and back safely?" Some built the spacecraft to carry humans to the Moon, enable surface operations and safely return astronauts to Earth. Others built the rockets that would launch these advanced spacecraft. In doing all this, NASA engineers and scientists helped lead the computing revolution from transistors to integrated circuits, the forebears to the microchip. An integrated circuit – a miniaturized electronic circuit that is used in nearly all electronic equipment today – is lighter weight, smaller and able to function on less power than the older transistors and capacitors. To suit the needs of the space capsule, NASA developed integrated circuits for use in the capsule's onboard computers. Additionally, computing advancements provided NASA with software that worked exactly as it was supposed to every time. That software lead to the development of the systems used today in retail credit-card swipe devices.

Some lesser-known benefits of the Apollo program include the technologies that commercial industries would then further advance to benefit humans right here on Earth. These "spinoffs" include technology that improved kidney dialysis, modernized athletic shoes, improved home insulation, advanced commercial and residential water filtration, and developed the freeze-drying technique for preserving foods.

Apollo was succeeded by missions that have continued to build a human presence in space and advance technologies on Earth. Hardware developed for Apollo was used to build America's first Earth-orbiting space station, Skylab. After Skylab, during the Apollo-Soyuz test project, American and Soviet spacecraft docked together, laying the groundwork for international cooperation in human spaceflight. American astronauts and Soviet cosmonauts worked together aboard the Soviet space station Mir, performing science experiments and learning about long-term space travel's effects on the human body. Eventually, the U.S. and Russia, along with 13 other nations, partnered to build and operate the International Space Station, a world-class science laboratory orbiting 400 kilometers (250 miles) above Earth, making a complete orbit every 90 minutes.

Graphic showing a possible configuration for the future lunar gateway

Although the configuration is not final, this infographic shows the current lineup of parts comprising the lunar Gateway. Image credit: NASA | › Full image and caption

And the innovations continue today. NASA is planning the Artemis mission to put humans on the Moon again in 2024 with innovative new technologies and the intent of establishing a permanent human presence. Working in tandem with commercial and international partners, NASA will develop the Space Launch System launch vehicle, Orion crew capsule, a new lunar lander and other operations hardware. The lunar Gateway – a small spaceship that will orbit the Moon and include living quarters for astronauts, a lab for science, and research and ports for visiting spacecraft – will provide access to more of the lunar surface than ever before. While at the Moon, astronauts will research ways to use lunar resources for survival and further technological development. The lessons and discoveries from Artemis will eventually pave a path for a future human mission to Mars.

Teach It

Use these standards-aligned lessons to help students learn more about Earth's only natural satellite:

As students head out for the summer, get them excited to learn more about the Moon and human exploration using these student projects:

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TAGS: K-12 Education, Teachers, Educators, Classroom, Engineering, Science, Students, Projects, Moon, Apollo, Summer

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

This feature was originally published on May 3, 2016.


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.

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 Does It Work?

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.

This lesson meets the following Next Generation Science and Common Core Math Standards:

NGSS Standards:

  • MS-PS2-2: Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.
  • HS-PS2-1: Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.
  • HS-PS2-1: Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

Common Core Math Standards:

  • Grade 8: Expressions and Equations A.4: Perform operations with numbers expressed in scientific notation, including problems where both decimal and scientific notation are used. Use scientific notation and choose units of appropriate size for measurements of very large or very small quantities (e.g., use millimeters per year for seafloor spreading). Interpret scientific notation that has been generated by technology.
  • High School: Algebra CED.A.4: Rearrange formulas to highlight a quantity of interest, using the same reasoning as in solving equations.
  • High School: Functions LE.A: Construct and compare linear, quadratic, and exponential models and solve problems.
  • High School: Functions BF.A.1: Write a function that describes a relationship between two quantities.
  • High School: Statistics and Probability ID.C: Interpret linear Models
  • High School: Number and Quantity Q.A.1: Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays."

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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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A glowing, orange ring outlines a black hole.

In the News

Accomplishing what was previously thought to be impossible, a team of international astronomers has captured an image of a black hole’s silhouette. Evidence of the existence of black holes – mysterious places in space where nothing, not even light, can escape – has existed for quite some time, and astronomers have long observed the effects on the surroundings of these phenomena. In the popular imagination, it was thought that capturing an image of a black hole was impossible because an image of something from which no light can escape would appear completely black. For scientists, the challenge was how, from thousands or even millions of light-years away, to capture an image of the hot, glowing gas falling into a black hole. An ambitious team of international astronomers and computer scientists has managed to accomplish both. Working for well over a decade to achieve the feat, the team improved upon an existing radio astronomy technique for high-resolution imaging and used it to detect the silhouette of a black hole – outlined by the glowing gas that surrounds its event horizon, the precipice beyond which light cannot escape. Learning about these mysterious structures can help students understand gravity and the dynamic nature of our universe, all while sharpening their math skills.

How They Did It

Though scientists had theorized they could image black holes by capturing their silhouettes against their glowing surroundings, the ability to image an object so distant still eluded them. A team formed to take on the challenge, creating a network of telescopes known as the Event Horizon Telescope, or the EHT. They set out to capture an image of a black hole by improving upon a technique that allows for the imaging of far-away objects, known as Very Long Baseline Interferometry, or VLBI.

Telescopes of all types are used to see distant objects. The larger the diameter, or aperture, of the telescope, the greater its ability to gather more light and the higher its resolution (or ability to image fine details). To see details in objects that are far away and appear small and dim from Earth, we need to gather as much light as possible with very high resolution, so we need to use a telescope with a large aperture.

That’s why the VLBI technique was essential to capturing the black hole image. VLBI works by creating an array of smaller telescopes that can be synchronized to focus on the same object at the same time and act as a giant virtual telescope. In some cases, the smaller telescopes are also an array of multiple telescopes. This technique has been used to track spacecraft and to image distant cosmic radio sources, such as quasars.

More than a dozen antennas pointing forward sit on barren land surrounded by red and blue-purple mountains in the distance.

Making up one piece of the EHT array of telescopes, the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has 66 high-precision antennas. Image credit: NRAO/AUI/NSF | + Expand image

The aperture of a giant virtual telescope such as the Event Horizon Telescope is as large as the distance between the two farthest-apart telescope stations – for the EHT, those two stations are at the South Pole and in Spain, creating an aperture that’s nearly the same as the diameter of Earth. Each telescope in the array focuses on the target, in this case the black hole, and collects data from its location on Earth, providing a portion of the EHT’s full view. The more telescopes in the array that are widely spaced, the better the image resolution.

This video shows the global network of radio telescopes in the EHT array that performed observations of the black hole in the galaxy M87. Credit: C. Fromm and L. Rezzolla (Goethe University Frankfurt)/Black Hole Cam/EHT Collaboration | Watch on YouTube

To test VLBI for imaging a black hole and a number of computer algorithms for sorting and synchronizing data, the Event Horizon Telescope team decided on two targets, each offering unique challenges.

The closest supermassive black hole to Earth, Sagittarius A*, interested the team because it is in our galactic backyard – at the center of our Milky Way galaxy, 26,000 light-years (156 quadrillion miles) away. (An asterisk is the astronomical standard for denoting a black hole.) Though not the only black hole in our galaxy, it is the black hole that appears largest from Earth. But its location in the same galaxy as Earth meant the team would have to look through “pollution” caused by stars and dust to image it, meaning there would be more data to filter out when processing the image. Nevertheless, because of the black hole’s local interest and relatively large size, the EHT team chose Sagittarius A* as one of its two targets.

An image showing a smattering of orange stars against the black backdrop of space with a small black circle in the middle and a rectangle identifying the location of the M87 black hole.

A close-up image of the core of the M87 galaxy, imaged by the Chandra X-ray Observatory. Image credit: NASA/CXC/Villanova University/J. Neilsen | + Expand image

A blue jet extends from a bright yellow point surrounded by smaller yellow stars.

This image from NASA's Hubble Space Telescope shows a jet of subatomic particles streaming from the center of M87*. Image credits: NASA and the Hubble Heritage Team (STScI/AURA) | + Expand image

The second target was the supermassive black hole M87*. One of the largest known supermassive black holes, M87* is located at the center of the gargantuan elliptical galaxy Messier 87, or M87, 53 million light-years (318 quintillion miles) away. Substantially more massive than Sagittarius A*, which contains 4 million solar masses, M87* contains 6.5 billion solar masses. One solar mass is equivalent to the mass of our Sun, approximately 2x10^30 kilograms. In addition to its size, M87* interested scientists because, unlike Sagittarius A*, it is an active black hole, with matter falling into it and spewing out in the form of jets of particles that are accelerated to velocities near the speed of light. But its distance made it even more of a challenge to capture than the relatively local Sagittarius A*. As described by Katie Bouman, a computer scientist with the EHT who led development of one of the algorithms used to sort telescope data during the processing of the historic image, it’s akin to capturing an image of an orange on the surface of the Moon.

By 2017, the EHT was a collaboration of eight sites around the world – and more have been added since then. Before the team could begin collecting data, they had to find a time when the weather was likely to be conducive to telescope viewing at every location. For M87*, the team tried for good weather in April 2017 and, of the 10 days chosen for observation, a whopping four days were clear at all eight sites!

Each telescope used for the EHT had to be highly synchronized with the others to within a fraction of a millimeter using an atomic clock locked onto a GPS time standard. This degree of precision makes the EHT capable of resolving objects about 4,000 times better than the Hubble Space Telescope. As each telescope acquired data from the target black hole, the digitized data and time stamp were recorded on computer disk media. Gathering data for four days around the world gave the team a substantial amount of data to process. The recorded media were then physically transported to a central location because the amount of data, around 5 petabytes, exceeds what the current internet speeds can handle. At this central location, data from all eight sites were synchronized using the time stamps and combined to create a composite set of images, revealing the never-before-seen silhouette of M87*’s event horizon. The team is also working on generating an image of Sagittarius A* from additional observations made by the EHT.

This zoom video starts with a view of the ALMA telescope array in Chile and zooms in on the heart of M87, showing successively more detailed observations and culminating in the first direct visual evidence of a supermassive black hole’s silhouette. Credit: ESO/L. Calçada, Digitized Sky Survey 2, ESA/Hubble, RadioAstron, De Gasperin et al., Kim et al., EHT Collaboration. Music: Niklas Falcke | Watch on YouTube

As more telescopes are added and the rotation of Earth is factored in, more of the image can be resolved, and we can expect future images to be higher resolution. But we might never have a complete picture, as Katie Bouman explains here (under “Imaging a Black Hole”).

To complement the EHT findings, several NASA spacecraft were part of a large effort to observe the black hole using different wavelengths of light. As part of this effort, NASA’s Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift Observatory space telescope missions – all designed to detect different varieties of X-ray light – turned their gaze to the M87 black hole around the same time as the EHT in April 2017. NASA’s Fermi Gamma-ray Space Telescope was also watching for changes in gamma-ray light from M87* during the EHT observations. If the EHT observed changes in the structure of the black hole’s environment, data from these missions and other telescopes could be used to help figure out what was going on.

Though NASA observations did not directly trace out the historic image, astronomers used data from Chandra and NuSTAR satellites to measure the X-ray brightness of M87*’s jet. Scientists used this information to compare their models of the jet and disk around the black hole with the EHT observations. Other insights may come as researchers continue to pore over these data.

Why It's Important

Learning about mysterious structures in the universe provides insight into physics and allows us to test observation methods and theories, such as Einstein’s theory of general relativity. Massive objects deform spacetime in their vicinity, and although the theory of general relativity has directly been proven accurate for smaller-mass objects, such as Earth and the Sun, the theory has not yet been directly proven for black holes and other regions containing dense matter.

One of the main results of the EHT black hole imaging project is a more direct calculation of a black hole’s mass than ever before. Using the EHT, scientists were able to directly observe and measure the radius of M87*’s event horizon, or its Schwarzschild radius, and compute the black hole’s mass. That estimate was close to the one derived from a method that uses the motion of orbiting stars – thus validating it as a method of mass estimation.

The size and shape of a black hole, which depend on its mass and spin, can be predicted from general relativity equations. General relativity predicts that this silhouette would be roughly circular, but other theories of gravity predict slightly different shapes. The image of M87* shows a circular silhouette, thus lending credibility to Einstein’s theory of general relativity near black holes.

An illustration of a black hole surrounded by a bright, colorful swirl of material. Text describes each part of the black hole and its surroundings.

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. Image credit: ESO | + Expand image

The data also offer some insight into the formation and behavior of black hole structures, such as the accretion disk that feeds matter into the black hole and plasma jets that emanate from its center. Scientists have hypothesized about how an accretion disk forms, but they’ve never been able to test their theories with direct observation until now. Scientists are also curious about the mechanism by which some supermassive black holes emit enormous jets of particles traveling at near light-speed.

These questions and others will be answered as more data is acquired by the EHT and synthesized in computer algorithms. Be sure to stay tuned for that and the next expected image of a black hole – our Milky Way’s own Sagittarius A*.

Teach It

Capture your students’ enthusiasm about black holes by challenging them to solve these standards-aligned math problems.

Model black-hole interaction with this NGSS-aligned lesson:

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TAGS: Black Hole, Teachable Moments, Science, K-12 Education, Teachers, Educators

  • Ota Lutz
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Illustration of spacecraft against a starry background

Update: March 15, 2019 – The answers to the 2019 NASA Pi Day Challenge are here! View the illustrated answer key


In the News

The excitement of Pi Day – and our annual excuse to chow down on pie – is upon us! The holiday celebrating the mathematical constant pi arrives on March 14, and with it comes the sixth installment of the NASA Pi Day Challenge from the Jet Propulsion Laboratory’s Education Office. This challenge gives students in grades 6-12 a chance to solve four real-world problems faced by NASA scientists and engineers. (Even if you’re done with school, they’re worth a try for the bragging rights.)

https://www.jpl.nasa.gov/edu/teach/activity/pi-in-the-sky-6/

Visit the "Pi in the Sky 6" lesson page to explore classroom resources and downloads for the 2019 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech/Kim Orr | + Expand image

Why March 14?

Pi, the ratio of a circle’s circumference to its diameter, is what is known as an irrational number. As an irrational number, its decimal representation never ends, and it never repeats. Though it has been calculated to trillions of digits, we use far fewer at NASA. In fact, 3.14 is a good approximation, which is why March 14 (or 3/14 in U.S. month/day format) came to be the date that we celebrate this mathematical marvel.

The first-known Pi Day celebration occurred in 1988. In 2009, the U.S. House of Representatives passed a resolution designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi.

The 2019 Challenge

This year’s NASA Pi Day Challenge features four planetary puzzlers that show students how pi is used at the agency. The challenges involve weathering a Mars dust storm, sizing up a shrinking storm on Jupiter, estimating the water content of a rain cloud on Earth and blasting ice samples with lasers!

›Take on the 2019 NASA Pi Day Challenge!

The Science Behind the Challenge

In late spring of 2018, a dust storm began stretching across Mars and eventually nearly blanketed the entire planet in thick dust. Darkness fell across Mars’ surface, blocking the vital sunlight that the solar-powered Opportunity rover needed to survive. It was the beginning of the end for the rover’s 15-year mission on Mars. At its height, the storm covered all but the peak of Olympus Mons, the largest known volcano in the solar system. In the Deadly Dust challenge, students must use pi to calculate what percentage of the Red Planet was covered by the dust storm.

The Terra satellite, orbiting Earth since 1999, uses the nine cameras on its Multi-Angle Imaging SpectroRadiometer, or MISR, instrument to provide scientists with unique views of Earth, returning data about atmospheric particles, land-surface features and clouds. Estimating the amount of water in a cloud, and the potential for rainfall, is serious business. Knowing how much rain may fall in a given area can help residents and first responders prepare for emergencies like flooding and mudslides. In Cloud Computing, students can use their knowledge of pi and geometric shapes to estimate the amount of water contained in a cloud.

Jupiter’s Great Red Spot, a giant storm that has been fascinating observers since the early 19th century, is shrinking. The storm has been continuously observed since the 1830s, but measurements from spacecraft like Voyager, the Hubble Space Telescope and Juno indicate the storm is getting smaller. How much smaller? In Storm Spotter, students can determine the answer to that very question faced by scientists.

Scientists studying ices found in space, such as comets, want to understand what they’re made of and how they interact and react with the environment around them. To see what molecules may form in space when a comet comes into contact with solar wind or sunlight, scientists place an ice sample in a vacuum and then expose it to electrons or ultraviolet photons. Scientists have analyzed samples in the lab and detected molecules that were later observed in space on comet 67P/Churyumov-Gerasimenko. To analyze the lab samples, an infrared laser is aimed at the ice, causing it to explode. But the ice will explode only if the laser is powerful enough. Scientist use pi to figure out how strong the laser needs to be to explode the sample – and students can do the same when they solve the Icy Intel challenge.

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Participate

Join the conversation and share your Pi Day Challenge answers with @NASAJPL_Edu on social media using the hashtag #NASAPiDayChallenge

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TAGS: Pi Day, K-12, STEM, Science, Engineering, Technology, Math, Pi, Educators, Teachers, Informal Education, Museums

  • Lyle Tavernier
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