Lyle Tavernier is an educational technology specialist at NASA's Jet Propulsion Laboratory. When he’s not busy working in the areas of distance learning and instructional technology, you might find him running with his dog, cooking or planning his next trip.

Image showing the difference in size and brightness between a full moon at apogee and a full moon at perigee, also called a "supermoon"

The term “supermoon” has been popping up a lot in the news and on social media over the past few years. But what are supermoons, why do they occur and how can they be used as an educational tool. Plus, are they really that super?

There’s a good chance you’ll hear even more about supermoons in the coming months. The full moon on December 3 marks the first and only supermoon of 2017, but it will be followed by two more in January and February 2018. Three supermoons in a row! Now is a great time to learn about these celestial events and get students exploring more about Earth’s only natural satellite.

Moon and Supermoon Lessons from NASA/JPL Edu

Lessons About the Moon

Explore our collection of standards-aligned lessons for grades 1-12.

How it Works

As the Moon orbits Earth, it goes through phases, which are determined by its position relative to Earth and the Sun. When the Moon lines up on the opposite side of Earth from the Sun, we see a full moon. The new moon phase occurs when the Moon and the Sun are lined up on the same side of Earth.

The Moon doesn’t orbit in a perfect circle. Instead, it travels in an ellipse that brings the Moon closer to and farther from Earth in its orbit. The farthest point in this ellipse is called the apogee and is about 405,500 kilometers from Earth on average. Its closest point is the perigee, which is an average distance of about 363,300 kilometers from Earth. During every 27-day orbit around Earth, the Moon reaches both its apogee and perigee.

Full moons can occur at any point along the Moon’s elliptical path, but when a full moon occurs at or near the perigee, it looks slightly larger and brighter than a typical full moon. That’s what the term “supermoon" refers to.

What makes a supermoon super? Watch this short animation to find out. Credit: NASA/JPL-Caltech

Because supermoon is not an official astronomical term, there is no definition about just how close to perigee the full moon has to be in order to be called “super." Generally, supermoon is used to refer to a full moon 90 percent or closer to perigee. (When the term supermoon was originally coined, it was also used to describe a new moon in the same position, but since the new moon isn’t easily visible from Earth, it’s rarely used in that context anymore.)

A more accurate and scientific term is “perigee syzygy.” Syzygy is the alignment of three celestial bodies, in this case the Sun, Moon and Earth. But that doesn’t quite roll off the tongue as easily as supermoon.

Why It’s Important

As the largest and brightest object in the night sky, the Moon is a popular focal point for many amateur and professional astronomers pointing their telescopes to the sky, and the source of inspiration for everyone from aspiring space scientists to engineers to artists.

The supermoon is a great opportunity for teachers to connect concepts being taught in the classroom to something students will undoubtedly be hearing about. Students can practice writing skills in a Moon journal, study Moon phases and apply their math skills to observing the supermoon. (Click here for related activities from JPL’s Education Office.)

Incorrect and misleading information about the Moon (and supermoons) can lead to confusion and frustration. It’s important to help students understand what to expect and be able to identify inaccurate info.

What to Expect


As with anything that moves closer to the person viewing it, the supermoon will appear bigger than an average full Moon. At its largest, it can appear 14% larger in diameter than the smallest full moon. Keep in mind that a 14% increase in the apparent size of something that can be covered with a fingernail on an outstretched arm won’t seem significantly bigger. Unlike side-by-side comparisons made in science and everyday life, students will not have seen the full moon for at least 30 days, and won’t see another for at least 30 more days. Comparing a supermoon with a typical full moon from memory is very difficult.

A nearly full Moon sets as the space shuttle Discovery sits atop Launch pad 39A at the Kennedy Space Center in Cape Canaveral, Florida, Wednesday, March 11, 2009. Photo Credit: (NASA/Bill Ingalls

While they make for great photographs, images like this one that rely on a special photographic technique aren't an accurate representation of what the supermoon will look like to the naked eye. Credit: NASA/Bill Ingalls | Full image and caption on Flickr

Graphic showing the position of the moon at apogee and perigee

A supermoon looks bigger than a "micromoon" (when the full moon is at apogee) because it's about 40,000 kilometers closer to Earth on average. Credit: NASA/JPL-Caltech

Graphic showing the position of the moon at apogee and perigee

It's nearly impossible to compare the apparent size of the supermoon with a micromoon from memory, but when seen side-by-side as in this graphic, it becomes clear. Credit: NASA/JPL-Caltech

Leading up to a supermoon, there are often misleading images on popular media. A technique that involves using a long telephoto lens to take photographs of the Moon next to buildings or other objects makes the Moon look huge compared with its surroundings. This effect can make for great photographs, but it has nothing to do with the supermoon. In fact, these photos can be taken during any Moon phase, but they will likely be used in stories promoting the supermoon.

There are also images that have been edited to inaccurately dramatize the size of the supermoon. Both of these can lead students, and adults, taking pictures with their cell phone to think that they’ve done something wrong or just aren’t cut out for observing the sky, which isn’t true!

Your students may have noticed that when they see a full moon low on the horizon, it appears huge and then seems to shrink as it rises into the night sky. This can happen during any full moon. Known as the Moon Illusion, it has nothing to do with a supermoon. In fact, scientists still aren’t sure what causes the Moon Illusion.


The full moon is bright and the supermoon is even brighter! Sunlight reflecting off the Moon during its full phase is bright enough to cast shadows on the ground. During a supermoon, that brightness can increase up to 30 percent as a result of the Moon being closer to Earth, a phenomenon explained by the inverse square law. (Introduce students to the inverse square law with this space-related math lesson for 6th- through 8th-graders.) As with the size of the Moon, students may not remember just how bright the last full moon was or easily be able to compare it. Powerful city lights can also diminish how bright a supermoon seems. Viewing it away from bright overhead street lights or outside the city can help viewers appreciate the increase in brightness.

What Not to Expect

A supermoon will not cause extreme flooding, earthquakes, fires, volcanic eruptions, severe weather, nor tsunamis, despite what incorrect and non-scientific speculators might suggest. Encourage your students to be good scientists and research this for themselves.

Teach It

The excitement and buzz surrounding a supermoon is a great opportunity to teach a variety of Moon topics with these lessons from JPL’s Education Office:

  • *NEW* Observing the Moon (Grades K-6) – Students identify the Moon’s location in the sky and record their observations over the course of the Moon-phase cycle in a journal.
  • *NEW* Measuring the Supermoon (Grades 5-12) – Students take measurements of the Moon during its full phases over multiple Moon cycles to compare and contrast results.
  • Moon Phases (Grades 1-6) – Students learn about the phases of the Moon by acting them out. In 30 minutes, they will act out one complete Moon cycle.
  • Whip Up a Moon-Like Crater (Grades 1-6) – Whip up a Moon-like crater with baking ingredients as a demonstration for students.
  • Modeling the Earth-Moon System (Grades 6-8) – Using an assortment of playground and toy balls, students will measure diameter, calculate distance and scale, and build a model of the Earth-Moon system.

TAGS: Supermoon, Moon Phases, Moon, Earth's Moon, What's Up, Astronomy, K-12, Educators

  • Lyle Tavernier

Animation of two black holes merging

Update – Oct. 3, 2017: Researchers Kip Thorne and Barry Barish of Caltech and Rainer Weiss of MIT have been awarded the 2017 Nobel Prize in Physics for their “decisive contributions to the LIGO detector and the observation of gravitational waves.”

Thorne, Barish and Weiss played key roles in making the LIGO project a reality through their research, leadership and development of technology to detect gravitational waves.

In a statement to Caltech, Thorne said the prize also belongs to the more than 1,000 scientists and engineers around the world who play a part on LIGO, the result of a long-term partnership between Caltech, MIT and the National Science Foundation.

› Read the Caltech press release

This story was originally published on March 23, 2016.

In the News

A century ago, Albert Einstein theorized that when objects move through space they create waves in spacetime around them. These gravitational waves move outward, like ripples from a stone moving across the surface of a pond. Little did he know that 1.3 billion years earlier, two massive black holes collided. The collision released massive amounts of energy in a fraction of a second (about 50 times as much as all of the energy in the visible universe) and sent gravitational waves in all directions. On September 14, 2015 those waves reached Earth and were detected by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Why It's Important

Einstein published the Theory of General Relativity in 1915. In it, he predicted the existence of gravitational waves, which had never been directly detected until now. In 1974, physicists discovered that two neutron stars orbiting each other were getting closer in a way that matched Einstein’s predictions. But it wasn’t until 2015, when LIGO’s instruments were upgraded and became more sensitive, that they were able to detect the presence of actual gravitational waves, confirming the last important piece of Einstein’s theory.

It's also important because gravitational waves carry information about their inception and about the fundamental properties of gravity that can’t be seen through observations of the electromagnetic spectrum. Thanks to LIGO’s discovery, a new field of science has been born: gravitational wave astronomy.

How They Did It

LIGO consists of facilities in Washington and Louisiana. Each observatory uses a laser beam that is split and sent down 2.5-mile (4-kilometer) long tubes. The laser beams precisely indicate the distance between mirrors placed at the ends of each tube. When a gravitational wave passes by, the mirrors move a tiny amount, which changes the distance between them. LIGO is so sensitive that it can detect a change smaller than 1/10,000 the width of a proton (10-19 meter). Having two observatories placed a great distance apart allows researchers to approximate the direction the waves are coming from and confirm that the signal is coming from space rather than something nearby (such as a heavy truck or an earthquake).

Teach It

Creating a model that demonstrates gravitational waves traveling through spacetime is as simple as making a gelatin universe!

› See the activity!

Middle school students can develop a model that shows gravitational waves traveling through spacetime while working toward the following Next Generation Science Standard:

  • MS-PS4-2 - Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.

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TAGS: Gravitational Waves, Teachable Moment, LIGO, Black Holes, Einstein

  • Lyle Tavernier

Update – Aug. 17, 2017: Two new lessons ("Measuring Solar Energy During an Eclipse" and "Modeling the Earth-Moon System") were added to the Teach It section below.

In the News

A satellite image of the Moon's shadow on Earth during a total solar eclipse

The Moon casts a shadow on Earth during a total solar eclipse over Europe in this image taken by a French astronaut on the Mir Space Station. Credit: CNES

This month marks the first time in 38 years that one of nature’s most awe-inspiring sights, a total solar eclipse, will be visible from the continental United States. And unlike the 1979 eclipse, the one on August 21 can be seen from coast to coast – something that hasn’t happened since 1918.

Millions of people are expected to travel to the 14 states that are in the path of totality – where the Moon will completely cover the disk of the Sun – while hundreds of millions more in every other state of the U.S. will be able to see a partial eclipse.

Whether you live in or are traveling to the path of totality, or will be able to step outside and view the partial eclipse from the comfort of your own home or school, the eclipse provides both an inspiring reason to look to the sky and opportunities to engage in scientific observations and discovery.

Animation of the Aug. 21, 2017 eclipse – Pi in the Sky 4 math problem

Teach It

Use these standards-aligned lessons and related activities to get your students excited about the eclipse and the science that will be conducted during the eclipse.

› Get started!

How it Works

Eclipses occur as the result of an alignment between the Sun, the Moon and Earth. Solar eclipses can only happen during the new moon phase, when the Moon’s orbit brings it between Earth and the Sun. At this time, the shadow cast by the moon could land on Earth, resulting in an eclipse. But most of the time, because the moon’s orbit is slightly titled, the moon’s shadow falls above or below Earth.

The time period when the Moon, Earth and the Sun are lined up and on the same plane is called an eclipse season. Eclipse seasons last about 34 days and occur just shy of every six months. A new moon during an eclipse season will cause the Moon’s shadow to fall on Earth, creating a solar eclipse.

graphic showing eclipse seasons
An eclipse season is the time period when the Moon, Earth and the Sun are lined up on the same plane. A new moon during an eclipse season will cause the Moon's shadow to fall on Earth, creating a solar eclipse. Image credit: NASA/JPL-Caltech

In addition to the proper alignment required for an eclipse, the distance between Earth, the Moon and the Sun also plays an important role. Even though the Moon is much smaller than the Sun (about 400 times smaller in diameter), the Sun and Moon appear about the same size from Earth because the Sun is about 400 times farther away than the Moon. If the Moon were farther from Earth, it would appear smaller and not cover the disk of the Sun. Similarly, if the Sun were closer to Earth, it would appear larger and the Moon would not completely cover it.

Why It’s Important

Total solar eclipses provide a unique opportunity for scientists to study the Sun and Earth from land, air and space, and allow the public to engage in citizen science!

Total eclipse image taken March 20, 2015 in Svalbard, Norway. Credit: S. Habbal, M. Druckmüller and P. Aniol

The sun's outer atmosphere (corona) and thin lower atmosphere (chromosphere) can be seen streaming out from the covered disk of the sun during a solar eclipse on March 20, 2015. Credit: S. Habbal, M. Druckmüller and P. Aniol

On a typical day, the bright surface of the Sun, called the photosphere, is the only part of the Sun we can see. During a total solar eclipse, the photosphere is completely blocked by the Moon, leaving the outer atmosphere of the Sun (corona) and the thin lower atmosphere (chromosphere) visible. Studying these regions of the Sun’s atmosphere can help scientists understand solar radiation, why the corona is hotter than the photosphere, and the process by which the Sun sends a steady stream of material and radiation into space.

Scientists measure incoming solar radiation on Earth, also known as insolation, to better understand Earth’s radiation budget – the energy emitted, reflected and absorbed by Earth. Just as clouds block sunlight and reduce insolation, the eclipse will block sunlight, providing a great opportunity to study how increased cloud cover can impact weather and climate. (Learn more about insolation during the 2017 eclipse here.)

Citizen scientists can get involved in collecting data and participating in the scientific process, too, through NASA’s Global Learning and Observations to Benefit the Environment, or GLOBE, program. During the eclipse, citizen scientists in the path of totality and in partial eclipse areas can measure temperature and cloud cover data and report it using the GLOBE Observer app to help further the study of how eclipses affect Earth’s atmosphere.

You can learn more about the many ways scientists are using the eclipse to improve their understanding of Earth, the Moon and the Sun here.

How to View It

Important! Do not look directly at the Sun or view the partial eclipse without certified eclipse glasses or a solar filter. For more information on safe eclipse viewing, visit the NASA Eclipse website.

When following proper safety guidelines, witnessing an eclipse is an unparalleled experience. Many “eclipse chasers” have been known to travel the world to see total eclipses.

The start time of the partial eclipse, when the edge of the Moon first crosses in front of the disk of the Sun, will depend on your location. You can click on your location in this interactive eclipse map to create a pin, which will show you the start and end time for the eclipse in Universal Time. (To convert from Universal Time to your local time, subtract four hours for EDT, five hours for CDT, six hours for MDT, or seven hours for PDT.) Clicking on your location pin will also show you the percent of Sun that will be eclipsed in your area if you’re outside the path of totality.

Aug 2017 eclipse map
This graphic shows the path of the Moon and Sun across the US during the Aug. 21, 2017 eclipse. The gray line represents the path of totality, while the Sun and Moon graphics flowing from top to bottom represent the percent of coverage for areas outside the path of totality. Image credit: NASA

If you are inside the approximately 70-mile-wide strip known as the path of totality, where the shadow of the Moon, or umbra, will fall on Earth, the total eclipse will be visible starting about an hour to 1.5 hours after the partial eclipse begins.

Only when the eclipse is at totality – and the viewer is in the path of totality – can eclipse glasses be removed. Look at the eclipse for anywhere from a few seconds to more than 2.5 minutes to see the Sun’s corona and chromosphere, as well as the darkened near side of the Moon facing Earth. As before, your viewing location during the eclipse will determine how long you can see the eclipse in totality.

graphic showing when its safe to remove your eclipse glasses if you are in the path of totality
Viewers should wear eclipse glasses or use a pinhole camera for the entirety of the partial eclipse. Those in the path of totality can remove their glasses only when the eclipse is in totality, which may last from a few seconds to more than 2.5 minutes depending on your location. Image credit: NASA

After totality ends, a partial eclipse will continue for an hour to 1.5 hours, ending when the edge of the Moon moves off of the disk of the Sun. Remember, wear eclipse glasses or use a pinhole camera for the entirety of the partial eclipse. Do not directly view the partial eclipse.

Animation of the pinhole camera project from NASA-JPL Education

Make a Pinhole Camera

Find out how to make your very own pinhole camera to safely view the eclipse in action.

› Get started!

To get an idea of what the eclipse will look like from your location and explore the positions of the Moon, Sun and Earth throughout the eclipse, see this interactive simulation.

For more information about the start of the partial eclipse, the start and duration of totality, and the percentage of the Sun eclipsed outside the path of totality, find your location on this interactive eclipse map.

NASA Television will host a live broadcast beginning at 9 a.m. PDT on Aug. 21 showing the path of totality and featuring views from agency research aircraft, high-altitude balloons, satellites and specially-modified telescopes. Find out how and where to watch, here

Teach It

Use these standards-aligned lessons and related activities to get your students excited about the eclipse and the science that will be conducted during the eclipse.

  • Epic Eclipse – Students use the mathematical constant pi to approximate the area of land covered by the Moon’s shadow during the eclipse.
  • Pinhole Camera – Learn how to make your very own pinhole camera to safely see a solar eclipse in action from anywhere the eclipse is visible, partial or full!
  • Moon Phases - Students learn about the phases of the Moon by acting them out. In 30 minutes, they will act out one complete, 30-day, Moon cycle.
  • NEW! Measuring Solar Energy During an Eclipse – Students use mobile devices to measure the impact a solar eclipse has on the energy received at Earth’s surface.
  • NEW! Modeling the Earth-Moon System – Students learn about scale models and distance by creating a classroom-size Earth-Moon system.
  • NASA GLOBE Observer – Students can become citizen scientists and collect data for NASA’s GLOBE Program using this app available for iOS and Android devices (eclipse update available starting August 18, 2017).

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TAGS: Eclipse, Solar Eclipse, Science, Pinhole Camera, K-12, Students, Educators

  • Lyle Tavernier

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.

Lesson: Ion Propulsion: Using Spreadsheets to Model Additive Velocity

Use It in the Classroom

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 in this standards-aligned lesson from NASA/JPL Education.

› Check it out!

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.

› See the lesson!

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

In the News

On April 19, an asteroid named 2014 JO25 will safely fly by Earth, passing at a distance of about 1.1 million miles (1.8 million kilometers) of the planet. This asteroid poses no threat to Earth and, in fact, asteroids safely fly by Earth quite regularly. What makes the upcoming close approach of asteroid 2014 JO25 unique is that it is a rather large asteroid, measuring about 2,000 feet (more than 600 meters) across. The last time an asteroid that large, or larger, came that close to Earth was in 2004. Not much is known about asteroid 2014 JO25 other than its approximate size, its trajectory (or path around the sun) and that its surface is about twice as reflective as that of the moon. When it passes by, the asteroid will be bright enough that small optical telescopes can be used to spot it in the night sky. Scientists around the world will also study the asteroid with telescopes to determine its composition and rotation and with radar that could reveal small surface features.

Modeling an Asteroid Lesson - NASA/JPL Education

Asteroid Resources for Educators

Explore our collection of standards-aligned lessons all about asteroids!

› View Asteroid Lessons from NASA!

Why It's Important

Asteroids are some of what remains of the material that formed our solar system about 4.6 billion years ago. Unchanged by the forces that have altered rocks on our home planet, the moon, Mars and other destinations around the solar system, asteroids provide a glimpse into what conditions were like when our solar system took shape. Studying the chemical and physical properties, as well as the location and motion of asteroids, is vital to helping us understand how the sun, planets and other solar system bodies came to be.

The study of asteroids is so important, in fact, that NASA has sent several spacecraft to study some of these objects up close. For example, in 2007, the Dawn mission was sent to explore the two largest objects in the asteroid belt, Vesta and Ceres. Dawn arrived at the giant protoplanet Vesta in 2011 and orbited it for about one year before flying to the dwarf planet Ceres, which it continues to orbit and study today. Data from the Dawn mission showed Vesta to be a fascinating world more closely related to terrestrial planets than to typical asteroids and revealed clues that indicate there is a large amount of ice and maybe subsurface liquid water on Ceres. In 2016, NASA launched a spacecraft called OSIRIS-REx, which is headed for an asteroid called Bennu. When it arrives in August 2018, OSIRIS-REx will map the asteroid and collect a sample to return to Earth.

Learn more about NASA's OSIRIS-REx spacecraft and its mission to asteroid Bennu.

But there is another reason studying asteroids and their movements is important: detecting nearby asteroids and predicting any hazard they might pose to Earth.

This graphic shows the orbits of all the known 'potentially hazardous asteroids,' numbering over 1,400 as of early 2013.

This graphic shows the orbits of all the known "potentially hazardous asteroids," numbering over 1,400 as of early 2013. Being classified as a potentially hazardous asteroid does not mean that an asteroid will impact Earth. None of these asteroids depicted is a worrisome threat over the next hundred years. By continuing to observe and track these asteroids, their orbits can be refined and more precise predictions made of their future close approaches and impact probabilities. Image credit: NASA/JPL-Caltech | › Full image and caption

Both 2014 JO25 and Bennu are considered near-Earth objects, meaning their orbits bring them closer than 1.3 astronomical units (AU) from the sun. For comparison, Earth is 1 AU from the sun, or about 93,000,000 miles (150,000,000 kilometers). Also, both asteroids are classified as “potentially hazardous.” A potentially hazardous asteroid is one with an orbit that comes within 0.05 AU (about 4,650,000 miles or 7,480,000 km) of Earth’s orbit and has an absolute magnitude, a measure of brightness, of 22 or less. (On the magnitude scale, the lower the number, the brighter the object.) Absolute magnitude can be an indicator of size, so in other words, potentially hazardous asteroids are large – typically larger than about 500 feet (140 meters) across – and could get close to Earth. Having a designation of “potentially hazardous” does not necessarily indicate the object is a threat to Earth. Scientists use the classification to indicate an object deserves increased attention.

Out of more than 730,000 known asteroids, about 16,000 are near-Earth objects, and there are currently 1,784 potentially hazardous asteroids. But the risks of a large asteroid like 2014 JO25 or Bennu impacting Earth are exceedingly rare. And thanks to the Center for Near Earth Object Studies, or CNEOS, at NASA’s Jet Propulsion Laboratory, we have a very good understanding of where many of these asteroids are and where they are headed. Supporting NASA’s Planetary Defense Coordination Office, CNEOS continually uses new data acquired by telescopes and submitted to the Minor Planet Center to update orbit calculations, analyzes asteroid impact risks over the next century and provides data for every near-Earth object.

How It Works

animated gif of asteroid 2013 MZ5 moving in a fixed background of stars

This animated gif shows asteroid 2013 MZ5 as seen by the University of Hawaii's PanSTARR-1 telescope. The asteroid moves relative to a fixed background of stars. Asteroid 2013 MZ5 is in the right of the first image, towards the top, moving diagonally left/down. Image credit: PS-1/UH

Detecting near-Earth objects, or NEOs, is done by comparing multiple images, taken several minutes apart, of the same region of the sky. The vast majority of the objects appearing in these images are stars and galaxies, and their positions are fixed in the same relative position on all the images. Because a moving near-Earth object would be in a slightly different position on each image while the background stars and galaxies are in the same positions, it can be easy to identify the moving target if it is bright enough.

Surveys done by NASA-supported ground-based telescopes – including Pans-STARRS1 in Maui, Hawaii, as well as the Catalina Sky Survey near Tucson, Arizona – have identified thousands of near-Earth objects. And a space-based telescope called NEOWISE has identified hundreds of others while scanning the skies at near-infrared wavelengths of light from its polar orbit around Earth. Many ground-based telescopes perform follow-up observations to further aid in orbit calculations and to study the physical properties of the objects.

One of the ways that NASA detects and tracks asteroids is with a space telescope called NEOWISE. The spacecraft uses infrared to detect and characterize asteroids and comets. Since December 2013, NEOWISE has discovered 72 near-Earth objects and characterized 439 others. Credit: NASA-JPL/Caltech

Once a near-Earth object is detected, its orbital characteristics are analyzed and astronomers determine if it is a potentially hazardous asteroid. This information is entered into CNEOS’ database, where it is continually updated and impact risks are monitored as new data becomes available.

Teach It

Asteroid 2014 JO25 won’t be this close for another 500 years, so now is a great opportunity to share this close approach with students and remind them that while it’s a close encounter by space standards, Earthlings need not be concerned. Try these standards-aligned lessons and activities with students:

  • Grades 1-6: Whip Up a Moon-Like Crater - Use baking ingredients to whip up a moon-like crater as an asteroid-impact demonstration for students. This activity works in classrooms, camps and at home.

  • Grades 3-5: Modeling an Asteroid - Students will shape their own asteroid models out of clay as a hands-on lesson in how asteroids form, what they are made of, and where they can be found in our solar system.

  • Grades 8-12: Math Rocks: A Lesson in Asteroid Dynamics - Students use math to investigate a real-life asteroid impact.

  • All ages: If you have a telescope, consider trying to view the asteroid at night. You’ll have to know where to look. Solar System Ambassador Eddie Irizarry shares how to find 2014 JO25 here. If you’re looking for more technical information about its location, use JPL’s Solar System Dynamics site to find the asteroid’s ephemeris.

Follow @AsteroidWatch on Twitter or visit the NASA Asteroid Watch website to find out more about upcoming close approaches.

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TAGS: Asteroid Flyby, Asteroids, Near-Earth Objects, NEOs, Asteroid 2014 JO25, Dawn, OSIRIS-REx, NEOWISE

  • Lyle Tavernier

NASA Pi Day Challenge Pi in the Sky 4 from NASA/JPL Edu

NASA Pi Day Challenge – Pi in the Sky 4 from NASA/JPL Edu – Answer Key

UPDATE: March 16, 2017 – An illustrated answer key for the 2017 NASA Pi Day Challenge is now available here.

Pi in the Sky 4 Answers – NASA Pi Day Challenge

Check your answers!

Were you able to solve these stellar mysteries using pi? Check your answers on our illustrated answer key and download the free "Pi in the Sky4" poster set.

NASA is giving space fans a reason to celebrate Pi Day, the March 14 holiday created in honor of the mathematical constant pi. For the fourth year in a row, the agency’s Jet Propulsion Laboratory has created an illustrated Pi Day Challenge featuring four math problems NASA scientists and engineers must solve to explore space. The challenge is designed to get students excited about pi and its applications beyond the classroom. This year’s problem set, designed for students in grade six through high school – but fun for all – features Mars craters, a total solar eclipse, a close encounter with Saturn, and the search for habitable worlds.

› Take the NASA Pi Day Challenge!

› Educators, get the standards-aligned Pi Day Challenge lesson and download the free poster and handouts. The answers to all four problems will be released in a companion infographic on March 16.

Read on for more about Pi Day, the science behind the 2017 problem set and to learn how NASA scientists and engineers use pi.

NASA Pi Day Challenge - Student Slideshow

Take the NASA Pi Day Challenge

Solve a Martian crater mystery, measure the size of the moon’s shadow during a total solar eclipse, get into a daring orbit around Saturn, and discover potentially habitable worlds beyond our solar system. You don’t have to be a NASA rocket scientist to do stellar math with pi.

Why March 14?

Pi is what’s known as an irrational number, meaning its decimal representation never ends and it never repeats. It has been calculated to more than one trillion digits, but NASA scientists and engineers actually use far fewer digits in their calculations (see “How Many Decimals of Pi Do We Really Need?”). The approximation 3.14 is often precise enough, hence the celebration occurring on March 14, or 3/14 (when written in US month/day format). The first known celebration occurred in 1988, and in 2009, the US 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.

Why It’s Important

While many of us celebrate by eating pi-themed pie and trying to memorize as many digits of pi as possible (the record is 70,030 digits), scientists and engineers at NASA take pi even further, using it in their day-to-day work exploring space!

“Finding the volume of a sphere, area of a circle (and thus volume of a cylinder) are well known applications of pi,” said Charles Dandino, a JPL engineer who designs robots for extreme environments. “But those relationships also form the basis for how stiff a structure is, how it will vibrate, and understanding how a design might fail.”

Rachel Weinberg works on the Orbiting Carbon Observatory 3, or OCO-3, instrument, which will track the distribution of carbon dioxide across Earth. She says pi came in handy during her studies at MIT and still does today for her work at JPL. “Just the other day during a meeting, the team went to the whiteboard and used pi to discuss the angles and dimensions of optical components on OCO-3,” she said.

Pi allows us to calculate the size and area of two- and three-dimensional shapes, says Anita Sengupta, a JPL engineer, who has worked on a variety of planetary missions. “In my career, pi has allowed me to calculate the size of a shield needed to enter the atmosphere of Venus and the size of a parachute that could safely land the Curiosity rover on the surface of Mars. Most recently we used pi in our calculations of the expanding atom cloud we will create for an experiment called the Cold Atom Laboratory, which will fly aboard the International Space Station.”

The Science Behind the Challenge

The Pi Day Challenge gives students a chance to take part in recent discoveries and upcoming celestial events, all while using math and pi just like NASA scientists and engineers.

“Students always want to know how math is used in the real world,” said Ota Lutz, a senior education specialist at JPL who helped create the Pi Day Challenge. “This problem set demonstrates the interconnectedness of science, math and engineering, providing teachers with excellent examples of cross-cutting concepts in action and students with the opportunity to solve real-world problems.”

Pi in the Sky 4 standards-aligned lesson - NASA Pi Day Challenge

NASA's Pi Day Challenge in the Classroom!

The NASA Pi Day Challenge is available as a standards-aligned lesson for grades 6-12. In the illustrated math problem set, students use pi to solve real-world science and engineering problems related to craters on Mars, a total solar eclipse, a daring orbit about Saturn, and the search for habitable worlds.

Here’s some of the science behind this year’s problem set.

The craters that cover Mars can tell us a lot about the Red Planet. Studying ejecta – the material blasted out during an impact – can tell us even more. Information about ejecta patterns even came up during a recent workshop to discuss and select the final candidates for the Mars 2020 rover landing site. For the first problem in our Pi Day Challenge, students use pi and the area and perimeter of two craters to identify which was made by an impactor that struck Mars at a low angle. Researchers found that low-angle impactors create an unusual ejecta pattern around craters on Mars. As part of the research, scientists are currently working to identify and catalog these craters.

The year 2017 brings a unique astronomical event to the United States for the first time in nearly 40 years! On August 21, 2017, a total solar eclipse will cross the continental United States. Starting in Oregon, the shadow of the moon will cross the country at more than 1,000 miles per hour, making its way to the Atlantic Ocean off the coast of South Carolina. Everyone inside the moon’s shadow will witness one of the most impressive sights nature has to offer. So how big is the shadow? In the second part of NASA’s Pi Day Challenge, students will use pi to calculate the area of the moon’s shadow on Earth during the total solar eclipse.

This year also marks the final chapter in the exciting story of NASA’s Cassini mission at Saturn. Since 2004, Cassini has been orbiting the ringed giant, vastly improving our understanding of the second largest planet in the solar system. After more than 12 years around Saturn, Cassini’s fuel is running low, so mission operators have devised a grand finale that will take the spacecraft closer to Saturn than ever before – inside the gap between the planet and its rings – and finally into Saturn’s cloud tops, where it will burn up. The finale is designed to prevent the spacecraft from crashing into and possibly contaminating any of Saturn’s scientifically intriguing moons. In the Pi Day Challenge, students will use pi to safely navigate the spacecraft on its final orbits and dive into Saturn.

Finally, students will investigate a relatively new and very exciting realm in astronomy, the search for habitable worlds. The discovery of exoplanets – worlds orbiting stars outside of our solar system – has changed our understanding of the universe. Until 1995, exoplanets hadn’t even been detected. Now, using the transit method – where planets are detected by measuring the light they block as they pass in front of a star – more than 2,300 exoplanets have been discovered. Recently, astronomers discovered a record seven Earth-size planets orbiting a single star called Trappist-1. Students will use pi to identify which of Trappist-1’s planets orbit in the star’s habitable zone – the area where liquid water could exist.

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Join the Conversation

  • Join the conversation and share your Pi Day Challenge answers with @NASA/JPL_Edu on social media using the hashtag #NASAPiDayChallenge
  • Pi Day: What’s Going ‘Round – Tell us what you’re up to this Pi Day and share your stories and photos with NASA.

Standards-Aligned Lessons


Facts and Figures



TAGS: Pi Day, Math, Science, Engineering, NASA Pi Day Challenge, K-12, Lesson, Activity, Slideshow

  • Lyle Tavernier

Brightened processed image of Saturn from Cassini to highlight the F ring

Update – Feb. 24, 2017: The deadline for the Cassini Scientist for a Day Essay Contest has passed. The winners will be announced in May 2017.

In the News

Next week, NASA’s Cassini spacecraft will go where no spacecraft has gone before when it flies just past the edge of Saturn’s main rings. The maneuver is a first for the spacecraft, which has spent more than 12 years orbiting the ringed giant planet. And it’s part of a lead-up to a series of increasingly awesome feats that make up the mission’s “Grand Finale” ending with Cassini’s plunge into Saturn on Sept. 15, 2017.

How They’ll Do It

graphic showing Cassini's orbits

Cassini's ring-grazing orbits, which will take place from late Novemeber 2016 through April 2017, are shown here in tan. The blue lines represent the path that Cassini took in the time leading up to the new orbits during its extended solstice mission. Image credit: NASA/JPL-Caltech/Space Science Institute | › Larger image

To prepare for the so-called “ring-grazing orbits,” which will bring the spacecraft within 56,000 miles (90,000 km) of Saturn, Cassini engineers have been slowly adjusting the spacecraft’s orbit since January. They do this by flying Cassini near Saturn’s large moon Titan. The moon’s gravity pulls on the spacecraft, changing its direction and speed.

On November 29, Cassini will use a big gravitational pull from Titan to get into an orbit that is closer to perpendicular with respect to the rings of Saturn and its equator. This orbit will send the spacecraft slightly higher above and below Saturn’s north and south poles, and allow it to get as close as the outer edge of the main rings – a region as of yet unexplored by Cassini.

This diagram shows Saturns ring-grazing and planet-grazing orbits

This graphic illustrates the Cassini spacecraft's trajectory, or flight path, during the final two phases of its mission. The view is toward Saturn as seen from Earth. The 20 ring-grazing orbits are shown in gray; the 22 grand finale orbits are shown in blue. The final partial orbit is colored orange. Image credit: NASA/JPL-Caltech/Space Science Institute | › Larger image

Why It’s Important

Cassini’s ring-grazing orbits will allow scientists to see features in Saturn's rings, up close, that they’ve only been able to observe from afar. The spacecraft will get so close to the rings, in fact, that it will pass through the dusty edges of the F ring, Saturn’s narrow, outermost ring. At that distance, Cassini will be able to study the rings like never before.

Among the firsts will be a “taste test” of Saturn’s rings from the inside out, during which Cassini will sample the faint gases surrounding the rings as well as the particles that make up the F ring. Cassini will also capture some of the best high-resolution images of the rings, and our best views of the small moons Atlas, Pan, Daphnis and Pandora, which orbit near the rings' outer edges. Finally, the spacecraft will do reconnaissance work needed to safely carry out its next planned maneuver in April 2017, when Cassini is scheduled to fly through the 1,500-mile (2,350-kilometer) gap between Saturn and its rings.

› Read more about what we might learn from Cassini's ring-grazing orbits.

These orbits are a great example of scientific research in action. Much of what scientists will be seeing in detail during these ring-grazing orbits are features that, despite Cassini’s 12 years at Saturn, have remained a mystery. These new perspectives could help answer questions scientists have long puzzled over, but they will also certainly lead to new questions to add to our ongoing exploration of the ringed giant.

Teach It

Cassini Scientist for a Day Essay Contest 2016 graphic

As part of the Cassini Scientist for a Day Essay Contest, students in grades 5-12 will write an essay describing which of these three targets would provide the most interesting scientific results. › Learn more and enter

What better way to share in the excitement of Cassini’s exploration than to get students thinking like NASA scientists and writing about their own questions and curiosities?

NASA’s Cassini Scientist for a Day Essay Contest, open to students in grades 5-12, encourages students to do just that. Participants research three science and imaging targets and then write an essay on which target would provide the most interesting scientific results, explaining what they hope to learn from the selected target. Winners of the contest will be featured on NASA’s Solar System Exploration website and get an opportunity to speak with Cassini scientists and engineers via video conference in the spring.

More information, contest rules and videos can be found here.

The deadline to enter is Feb. 24, 2017.

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TAGS: Cassini, Saturn's Rings, Saturn, Grand Finale, Spacecraft, Missions, K-12, Lessons, Activities, Language Arts, Science, Essay Contest

  • Lyle Tavernier

UPDATE - May 9, 2016: NASA's Solar Dynamics Observatory, or SDO, spacecraft captured stunning images of the May 9, 2016 transit of Mercury. Visit the mission's Transit of Mercury page to see a collection of videos of the transit compiled using SDO images. And have students play "Can You Spot Mercury?" in our educational slideshow. 

In the News

It only happens about 13 times per century and hasn’t happened in nearly a decade, but on Monday, May 9, Mercury will transit the sun. 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. (Transits of Venus are even more rare. The next one won't happen until 2117!) On May 9, as Mercury passes in front of the sun, 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.

CAUTION: Looking directly at the sun can cause permanent vision damage – see below for tips on how to safely view the transit.

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 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 (the transit of Venus wasn’t visible from Europe). It was soon understood that transits could be used as an opportunity to measure the apparent diameter – how large a planet appears from Earth – with great accuracy.

In 1677, Edmond Halley observed the transit of Mercury and realized that the parallax shift of the planet – the variation in Mercury’s apparent position against the disk of the sun as seen by observers at distant points on Earth – could be used to accurately measure the distance between the sun and Earth, which wasn’t known at the time.

Today, radar is used to measure the distance between Earth and the sun with greater precision than can be found using transit observations, but the transit of Mercury still provides 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 in an ultra-thin atmosphere of gases called an exosphere. Scientists want to better understand the composition and density of the gases that make up 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.”

Mercury transits the sun in 2006
This image of Mercury passing in front of the sun was captured on Nov. 8, 2006 by the Solar Optical Telescope, one of three primary instruments on the Hinode spacecraft. Image credit: Hinode JAXA/NASA/PPARC

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, called exoplanets, that are otherwise obscured from view by the light of the 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 mission has found more than 1,000 exoplanets by looking for this telltale drop in brightness.

illustration of how transits are used to find exoplanets
This diagram shows how scientists use the light curves of distant stars to search for planets outside our solar system. A drop in the light curve, as illustrated here, is a good indication that there's a planet orbiting the observed star. Credit: NASA Ames

The Kepler mission measures the brightness of stars. The data will look like an EKG showing the heart beat. Whenever a planet passes in front of its parent star as viewed from the spacecraft, a tiny pulse or beat is produced. From the repeated beats, we can detect and verify the existence of Earth-size planets and learn about the orbit and size of the planet. Video credit: NASA Ames and Dana Berry

Additionally, scientists have begun exploring the exospheres of exoplanets. By observing the spectra of the light that passes through an exosphere – similar to how we study Mercury’s exosphere – scientists are beginning to understand the evolution of exoplanet atmospheres as well as the influence of stellar wind and magnetic fields.

Watch It

Mercury will appear as a tiny dot on the sun’s surface and will require a telescope or binoculars with a special solar filter to see. 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 solar filter.

The transit of Mercury will begin at 4:12 a.m. PDT, meaning by the time the sun rises on the West Coast, Mercury will have been transiting the sun for nearly two hours. Fortunately, it will take seven and a half hours for Mercury to completely cross the sun’s face, so there will be plenty of time for West Coast viewers to witness this event. See the transit map to learn when and where the transit will be visible.

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

NASA also will stream a live program on NASA TV and the agency’s Facebook page from 7:30 to 8:30 a.m. PDT (10:30 to 11:30 a.m. EDT) -- an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA.

Teach It

Here are two ways to turn the transit of Mercury into a lesson for students.

  • Exploring Exoplanets with Kepler - Students use math concepts related to transits to discover real-world data about Mercury, Venus and planets outside our solar system.
  • Pi in the Sky 3 - Try the "Sun Screen" problem on this illustrated math problem set that has students calculate the percentage drop in sunlight reaching Earth when Mercury transits.

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Transit Resources:

Exoplanet Resources:

TAGS: Transit, Transit of Mercury, Mercury, Venus, Sun, Exoplanets, Teach, Classroom Activities, Lessons,

  • Lyle Tavernier

Cartoon animation of NASA-JPL spacecraft

UPDATE: March 16, 2016 – The answers the the NASA Pi Day Challenge are now available as an illustrated answer key. Download a poster version of the answer key on the "Pi in the Sky 3" activity page.

NASA Pi Day Challenge Answer Key

› Check your answers!

This post was originally published on March 9, 2016

In the News

Pi Day, the informal holiday beloved by math enthusiasts – and even by the math averse – is almost here! March 14 marks the yearly celebration of the mathematical constant (pi), which represents the ratio of a circle’s circumference to its diameter. More than just a number for mathematicians, pi has all sorts of applications in the real world, including on missions developed by NASA’s Jet Propulsion Laboratory. And as a holiday that encourages more than a little creativity – whether it’s making pi-themed pies or reciting from memory as many of the never-ending decimals of pi as possible (the record is 70,030 digits) – it’s a great way to have fun and celebrate the M in STEM.

Why March 14?

Pi is what’s known as an irrational number, meaning its decimal representation never ends and it never repeats. It has been calculated to more than one trillion digits, but 3.14 is often a precise enough approximation, hence the celebration occurring on March 14, or 3/14 (when written in US month/day format). The first known celebration occurred in 1988, and in 2009, the US 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.

Why It’s Important

Pi Day is lots of fun, but its importance lies in the role that pi plays in the everyday work of scientists and engineers at JPL.

Fred Calef, a geospatial information scientist at JPL, uses pi to make measurements – like perimeter, area and volume – of features on Mars. “I use pi to measure the circularity of features, or how round or compact they are," said Calef. "Craters become more elliptical if the projectile hits the surface at a lower angle, so I use pi to measure how round a crater is to see if it impacted at a low angle.”

"We use pi every day commanding rovers on Mars," said Hallie Gengl, a rover planner for the Mars Exploration Rover Opportunity, "Everything from taking images, turning the wheels, driving around, operating the robotic arm, and even talking to Earth.”

Bryana Henderson, who specializes in planetary ices, uses lasers to explode ice samples and study their composition. "I use pi to calculate the width of my laser beam, which in turn can be used to calculate the amount of energy, or fluence, that hits my ice sample," said Henderson. "A larger fluence equals a bigger explosion in the ice, so this is a very important parameter for us."

The Pi Day Challenge

JPL has released the third installment of its popular Pi Day challenge, which gives students and the public a chance to put their pi skills to the test to solve some of the same problems NASA scientists and engineers do. The set of four illustrated math problems are compiled into a graphic (as well as classroom handouts) designed for students in grade 4 through high school – but fun for all!

Pi in the Sky 3 activity

› Check out this year's Pi Day challenge!

This year’s problem set shows how pi can be used to map the surface of Saturn’s hazy moon Titan, track the Mars Reconnaissance Orbiter as it explores the Red Planet, keep Earth’s satellites powered as Mercury transits the sun, and put the Juno spacecraft into orbit around Jupiter.

“For Pi Day, we like to give students and the public a glimpse into how math is used at JPL through questions that feature current events involving our space missions,” said Ota Lutz, an education specialist at JPL who helped create the problem set. “For instance, to put the Juno spacecraft into orbit around Jupiter on July 4, engineers will have to slow the spacecraft just the right amount. In the Pi Day challenge, students use pi to calculate that change in velocity.”

In the challenge, students will also use pi to calculate how much sunlight is blocked by our solar system’s innermost planet as it passes between Earth and the sun. This year, Pi Day comes just a few months before the May 9 transit of Mercury, making this a timely problem.

On March 16, the answers to all four problems and the steps needed to find those answers will be released in a companion infographic on the Pi Day challenge activity page.

In addition to the Pi Day challenge, JPL is inviting the public to share their Pi Day pictures and stories online. On March 14, JPL will join in on the fun with Pi Day photos and stories from the lab.

› Share Your Pi Day photos and stories

To see a compilation of all 12 Pi Day challenge questions optimized for mobile devices and screen readers, visit:

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Pi Day Challenges


Facts and Figures



TAGS: pi, pi day, math, mathematics

  • Lyle Tavernier