NASA/JPL education specialists share tips on how to engage students in science, technology, engineering and mathematics using the latest NASA science and mission news.

Side-by-side satellite images of the sand fire that show the heigh of the smoke

In the News

You didn’t need to check social media, read the newspaper or watch the local news to know that California wildfires were making headlines this summer. Simply looking up at a smoke-filled sky was enough for millions of people in all parts of the state to know there was a fire nearby.

Fueled by high temperatures, low humidity, high winds and five years of vegetation-drying drought, more than 4,800 fires have engulfed 275,000-plus acres across California already this year. And the traditional fire season – the time of year when fires are more likely to start, spread and consume resources – has only just begun.

With wildfires starting earlier in the year and continuing to ignite throughout all seasons, fire season is now a year-round affair not just in California, but also around the world. In fact, the U.S. Forest Service found that fire seasons have grown longer in 25 percent of Earth's vegetation-covered areas.

For NASA's Jet Propulsion Laboratory, which is located in Southern California, the fires cropping up near and far are a constant reminder that its efforts to study wildfires around the world from space, the air and on the ground are as important as ever.

JPL uses a suite of Earth satellites and airborne instruments to help better understand fires and aide in fire management and mitigation. By looking at multiple images and types of data from these instruments, scientists compare what a region looked like before, during and after a fire, as well as how long the area takes to recover.

While the fire is burning, scientists watch its behavior from an aerial perspective to get a big-picture view of the fire itself and the air pollution it is generating in the form of smoke filled with carbon monoxide and carbon dioxide.

Natasha Stavros, a wildfire expert at JPL, joined Zach Tane with the U.S. Forest Service during a Facebook Live event (viewable below) to discuss some of these technologies and how they're used to understand wildfire behavior and improve wildfire recovery.

Animation of the FireSat network of satellites capturing wildfires on Earth

This animation shows how FireSat would use a network of satellites around the Earth to detect fires faster than ever before.

Additionally, JPL is working with a startup in San Francisco called Quadra Pi R2E to develop FireSat, a global network of satellites designed to detect wildfires and alert firefighting crews faster. When completed in June 2018, the network's array of more than 200 satellites will use infrared sensors to detect fires around the world much faster than is possible today. Working 24 hours a day, the satellites will be able to automatically detect fires as small as 35 to 50 feet wide within 15 minutes of when they begin. And within three minutes of a fire being detected, the FireSat network will notify emergency responders in the area.

Using these technologies, NASA scientists are gaining a broader understanding of fires and their impacts. 

Why It's Important

One of the ways we often hear wildfires classified is by how much area they have burned. Though this is certainly of some importance, of greater significance to fire scientists is the severity of the fire. Wildfires are classified as burning at different levels of severity: low, medium, and high. Severity is a function of intensity, or how hot the fire was, and its spread rate, or the speed at which it travels. A high-severity fire is going to do some real damage. (Severity is measured by the damage left after the fire, but can be estimated during a fire event by calculating spread rate and measuring flame height which indicates intensity.)

Google Earth image showing fire severity
This image, created using data imported into Google Earth, shows the severity of the 2014 King Fire. Green areas are unchanged by the fire; yellow equals low severity; orange equals moderate severity; and red equals high severity. A KMZ file with this data is available in the Fired Up Over Math lesson linked below. Credit: NASA/JPL-Caltech/E. Natasha Stavros.

The impacts of wildfires range from the immediate and tangible to the delayed and less obvious. The potential for loss of life, property and natural areas is one of the first threats that wildfires pose. From a financial standpoint, fires can lead to a downturn in local economies due to loss of tourism and business, high costs related to infrastructure restoration, and impacts to federal and state budgets.

The release of greenhouse gases like carbon dioxide and carbon monoxide is also an important consideration when thinking about the impacts of wildfires. Using NASA satellite data, researchers at the University of California, Berkeley, determined that between 2001 and 2010, California wildfires emitted about 46 million tons of carbon, around five to seven percent of all carbon emitted by the state during that time period.

Animation showing Carbon Dioxide levels rising from the Station Fire in Southern California.
This animation from NASA's Eyes on the Earth visualization program shows carbon monoxide rising (red is the highest concentration) around Southern California as the Station Fire engulfed the area near JPL in 2009. Image credit: NASA/JPL-Caltech

In California and the western United States, longer fire seasons are linked to changes in spring rains, vapor pressure and snowmelt – all of which have been connected to climate change. Wildfires serve as a climate feedback loop, meaning certain effects of wildfires – the release of CO2 and CO – contribute to climate change, thereby enhancing the factors that contribute to longer and stronger fire seasons.

While this may seem like a grim outlook, it’s worth noting that California forests still act as carbon sinks – natural environments that are capable of absorbing carbon dioxide from the atmosphere. In certain parts of the state, each hectare of redwood forest is able to store the annual greenhouse gas output of 500 Americans.

Studying and managing wildfires is important for maintaining resources, protecting people, properties and ecosystems, and reducing air pollution, which is why JPL, NASA and other agencies are continuing their study of these threats and developing technologies to better understand them.

Teach It

Have your students try their hands at solving some of the same fire-science problems that NASA scientists do with these two lessons that get students in grades 3 through 12 using NASA data, algebra and geometry to approximate burn areas, fire-spread rate and fire intensity:

  • Fired Up Over Math: Studying Wildfires from Space - In this activity, younger students use arithmetic, scale, and math tiles; middle school students employ rate and partial polygon area formulas; and high school students use Google Earth software embedded with recent NASA wildfire data to make inferences about fire severity.

  • Pixels on Fire – In this technology-based lesson, students detect mock fires using mobile devices and study NASA data visualizations to determine when actual California wildfires started.

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Lyle Tavernier was a co-author on this feature.

TAGS: teachable moments, wildfires, science

  • Ota Lutz

ET-94 is towed through Los Angeles on May 21, 2016.

ET-94 is towed through Los Angeles on May 21, 2016.

ET-94 is towed ashore in Marina del Rey in Los Angeles

ET-94 comes into port in Marina del Rey in Los Angeles

In the News

History was made recently as the last-existing, flight-qualified external fuel tank for NASA's Space Shuttle Program made a 16.5-mile crawl through the streets of Los Angeles to its new home at the California Science Center. On May 21, 2016, the tank, a nearly 154-foot long, more than 65,000-pound behemoth dubbed ET-94, was towed from the port in Marina del Rey (where it arrived after another epic voyage) to the science center. Eventually, it will be displayed with the space shuttle Endeavour and two solid rocket boosters in launch configuration – looking like it's ready to blast into space.

How They Did It

The route map through Los Angeles for NASA's space shuttle external fuel tank ET-94
This map shows the 16.5-mile route ET-94 took through Los Angeles to arrive at the California Science Center. Image credit: NASA/JPL-Caltech
› Larger image | › Interactive Google Map

Transporting a large object such as the external tank is no small job. Shuttle external tanks were routinely transferred from their manufacture and assembly point at NASA's Michoud Assembly Facility in New Orleans to the Kennedy Space Center in Florida by way of barge. However, the trip to California is a bit more involved.

In April, ET-94 boarded a barge as usual, but this time traveled west, through the Panama Canal to Marina del Rey in Los Angeles. On May 18, the tank arrived, and three days later, was towed through the streets of Los Angeles – streets that were not designed to accommodate a giant rocket fuel tank!

› Watch the full route from New Orleans to Los Angeles taken by the shuttle's external tank

Los Angeles has some experience with this sort of challenge as the space shuttle orbiter Endeavour traveled a similar route from Los Angeles International Airport to the California Science Center in October 2012. Though Endeavour is wider, taller and heavier, ET-94 is longer. Resting on its side, the tank is half the length of a football field. So it presents a different set of navigational challenges – which, coincidentally, make for some great math problems.

As does this bit of external fuel tank history ...

A Slice of History

Most people will recognize the external tank as the giant orange structure that was attached to the shuttle to supply fuel to the shuttle's main engines during liftoff. Space shuttle external tanks carried freezing cold liquid hydrogen and liquid oxygen and were the only non-reusable part of what was called the Space Transportation System, or STS. But the tanks weren't always orange.

NASA's Endeavour STS-134 on launch pad at Kennedy Space Flight Center.
NASA's Endeavour STS-134 on launch pad at Kennedy Space Flight Center in Florida. The orange structure behind the shuttle is an external fuel tank. Image credit: NASA

During the first shuttle missions, engineers were worried that the sun's ultraviolet radiation might damage the insulating foam, so the tanks were painted white. Because the white latex paint had to cover such a large surface area, it added a whopping 600 pounds to the already hefty tanks, which in their earliest iteration were called standard-weight tanks, or SWTs, and made of aluminum alloy 2219 welded via tungsten arc welding and coated with an inch-thick layer of polyisocyanurate foam. They weighed 77,086 empty and fuel added an extra 1,589,577 pounds!

STS-1 Launches from NASA's Kennedy Space Flight Center in Florida.
STS-1 launches from Kennedy Space Flight Center in Florida. For the first two shuttle missions, engineers painted the external fuel tanks white because of worries about ultraviolet radiation damaging the tanks' insulating foam. Image credit: NASA

After the first two STS missions, engineers agreed that the sun's ultraviolet radiation merely caused the insulating foam to change color from its original tan to the familiar dark orange and did not pose a structural risk, so the use of white paint was discontinued. The saved poundage allowed subsequent space shuttle missions to carry an additional 600 pounds of science experiments.

Ever striving to lighten the load of the STS to make room for more science payloads, engineers developed the next iteration of external tanks, called lightweight tanks, or LWTs, using weight-shedding techniques including eliminating portions of stringers (structural stiffeners running the length of the hydrogen tank), using fewer stiffener rings, and modifying major frames in the hydrogen tank. This new tank provided a 6,426-pound reduction in specification weight that further evolved to an actual weight of 65,081 pounds for ET-94.

The final iteration of the external tank, called a super lightweight tank, or SLWT, shed an amazing 18,586 pounds from the very first specifications by using a new aluminum-lithium alloy (Al-Li 2195) and some new welding techniques.

Why It's Important

In 2003, disaster struck space shuttle Columbia during the STS-107 mission. The shuttle was fueled by ET-94's sister tank, ET-93, and as the only remaining lightweight tank in existence, ET-94 was heavily analyzed to examine the role played in the incident by the tank's external insulating foam. Several chunks of foam were removed from the tank during the analysis, necessitating future repair work to return it to its original appearance.

ET-94 on a barge in Marina del Rey, California.
ET-94 arrives in Marina del Rey, California on May 18, 2016. The areas where ET-94's insulating foam were removed for testing can be seen (as light orange patches) in the upper left portion of the photo. Image credit: NASA/JPL-Caltech/David Seidel

After analysis was complete, the tank resided at the Michoud Assembly Facility, awaiting an opportunity to fly to space that never came, as it could not compete with the svelteness of the new super-lightweight tanks and would require some weighty upgrades to meet new safety standards. Eventually, NASA donated ET-94 to the California Science Center for public display. When finalized, the display will be the only complete stack of STS flight hardware in existence.

Teach It

Help your students apply their math problem-solving skills to this history-making event. While considering the challenges encountered in moving a giant fuel tank through the streets of Los Angeles, younger students can practice their number sense skills and older students can solve problems using formulas – plus use mapping technology to help ET-94 find its way to the California Science Center!

› Explore the lesson

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TAGS: External Fuel Tank, ET-94, Space Shuttle, Endeavour, Columbia, STS, Space Transportation System

  • Ota Lutz

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

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

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.

› 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

Animation of two black holes merging

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

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

Artist concept of NASA's Juno spacecraft

In the News

NASA’s Juno mission, the first solar-powered mission to Jupiter, has become the farthest solar-powered spacecraft ever! Juno, and its eight science instruments designed to study the interior of Jupiter, has passed the mark previously held by the European Space Agency’s Rosetta mission and reached a distance of 5.3 astronomical units from the sun (an astronomical unit is equal to the average distance between Earth and the sun – about 149.6 million kilometers). Using only power from the sun, Juno will complete the five-year trip to Jupiter in July 2016 and begin studying the solar system’s most massive world in an attempt to better understand the origins of the planet, and in turn, our solar system.

What Made It Possible

Just as a bright source of light dims as you move away from it, sunlight becomes less intense the farther a spacecraft travels from the sun, limiting the amount of power that can be generated using solar cells. Previous missions that visited Jupiter, like Galileo, Voyager 1 and Voyager 2, couldn’t use solar power and instead used radioisotope thermoelectric generators (RTGs) to supply power.

Advances in solar panel efficiency along with improvements in the way spacecraft and their instruments use power have recently made solar power a viable option for spacecraft heading as far as Jupiter – though going beyond will require further technological advances.

Engineers designed Juno with three massive solar panels, each nearly 30 feet long. Combined, they provide Juno with 49.7 m2 of active solar cells. Once it reaches Jupiter, Juno will generate more than 400 watts of power, which may not sound like a lot, but it’s an impressive feat at so great a distance. For comparison, Juno’s solar panels can generate about 14 kilowatts near Earth.

NASA's Juno spacecraft being prepped for launch
Technicians stow for launch a solar array on NASA's Juno spacecraft. Each of Juno's three solar arrays is 9 feet (2.7 meters wide), by 29 feet (8.9 meters long). Image credit: NASA/JPL-Caltech/KSC

Teach It

Juno's record-setting achievement translates into a powerful lesson in exponents.

> Get the problem set!

Middle school students and other students working with exponents will find challenging, real-world applications related to the work being done here at NASA while addressing four Common Core Math standards:

  • Grade 6: Expressions and Equations A.1 - "Write and evaluate numerical expressions involving whole-number exponents."
  • Grade 6: Expressions and Equations A.2 - "Write, read, and evaluate expressions in which letters stand for numbers."
  • Grade 6: Expressions and Equations A.2.C - "Evaluate expressions at specific values of their variables. Include expressions that arise from formulas used in real-world problems. Perform arithmetic operations, including those involving whole-number exponents, in the conventional order when there are no parentheses to specify a particular order (Order of Operations)."
  • Grade 8: Expressions and Equations A.1 - "Know and apply the properties of integer exponents to generate equivalent numerical expressions. For example, 32 × 3-5 = 3-3 = 1/33 = 1/27."

Explore More!

  • Juno mission website - News, resources and updates on NASA's mission to Jupiter.

  • Eyes on the Solar System - Take a virtual journey to Jupiter with Juno (scroll to "Solar System Tours" and click on Juno).

  • To Jupiter with JunoCam! - Find out how classrooms can participate in the Juno mission to Jupiter using the spacecraft's on-board educational camera.

  • Infographic: Solar Power Explorers - This graphic shows how NASA’s Juno mission to Jupiter became the most distant solar-powered explorer and influenced the future of space exploration powered by the sun.

TAGS: Juno, Jupiter, Exponents, Math, Lesson, Activity, Teachable Moment

  • Lyle Tavernier

Saturn's moon Enceladus

In the News

Saturn’s icy moon Enceladus has been making news lately, and it could make even bigger news soon! In September, scientists confirmed that there was a global ocean underneath Enceladus’ thick icy shell. That was just the latest in a long history of exciting finds dating back to the beginning of NASA’s Cassini-Huygens Mission to Saturn in 2004 that have helped scientists to better understand this fascinating world!

Even while Cassini was still on its way to Saturn, its Cosmic Dust Analyzer detected microscopic grains of silica (tiny grains of sand). On Earth, grains of silica similar in size to those detected near Saturn form when hydrothermal activity -- the processes involving heated water beneath Earth’s surface or ocean -- causes salty water to chemically interact with rocky material to form silica. But where were these grains coming from in the space around Saturn?

In 2005, scientists were surprised to find out that Enceladus’ south pole is both warmer than expected and warmer than the surrounding areas, suggesting there is a heat source inside Enceladus. Not only that, but they also discovered long parallel cracks in the ice on Enceladus’ south pole. The young age of these cracks, nicknamed Tiger Stripes, meant that Saturn’s icy moon is a geologically active place.

Color image of the cracks, or Tiger Stripes, on the South Pole of Saturn's moon Enceladus
This enhanced color view of Saturn's moon Enceladus shows the south polar terrain, where jets of material spray out form long cracks called Tiger Stripes. Image credit: NASA/JPL-Caltech/Space Science Institute | Full image and caption

Heat map of Saturn's moon Enceladus
This image shows the infrared (heat) radiation at the south pole of Saturn's moon Enceladus, including the dramatic warm spot centered on the pole near the moon's Tiger Stripes feature. The data were taken during the spacecraft's third flyby of Enceladus on July 14, 2005. Image credit: NASA/JPL-Caltech/Space Science Institute | Full image and caption

Another piece of this puzzle was put in place with the discovery of jets of material spraying out of the Tiger Stripes. Studies have shown these jets are composed of mostly of water vapor, tiny ice particles and small amounts of other material (for example, microscopic silica grains). Together, over 100 jets make up a feature called a plume. Investigating further, scientists have hypothesized that these silica grains are the result of hydrothermal activity on the ocean floor below Enceladus’ icy crust.

Movie of the Plume on Saturn's moon Enceladus
Jets of icy particles burst from Saturn’s moon Enceladus in this brief movie sequence of four images taken on Nov. 27, 2005. Credit: NASA/JPL-Caltech/Space Science Institute | Full image and caption

On October 28, Cassini will fly right through the plume jetting out of Enceladus’ south pole at an altitude of only 49 kilometers (30 miles) – closer than any previous passes directly through the plume! This is an exciting moment in the mission -- one that allows science teams to use a combination of tools on board the spacecraft to strengthen previous findings and potentially make new discoveries.

Why It's Important

Cassini will use its Cosmic Dust Analyzer to study the solid plume particles and an instrument called the Ion and Neutral Mass Spectrometer to “sniff” the gas vapor in order to determine the composition of the jets. Specifically, the latter instrument is looking for H2, or molecular hydrogen. Finding H2 in the plume will strengthen the evidence that hydrothermal activity is occurring on Enceladus’ ocean floor. And the amount of H2 in the plume, will tell scientists just how much activity is happening.

In addition to indicating that hydrothermal activity is taking place, figuring out the amount of hydrothermal activity will give scientists a good indication of how much internal energy there is deep inside Enceladus.

That Cassini is making a pass through the plume at such a low, 49-kilometer-high altitude is also important. Organic compounds -- substances formed when carbon bonds with hydrogen, nitrogen, oxygen, phosphorus or sulfur -- tend to be heavy and would fall out of the plume before reaching the heights of Cassini’s previous, higher altitude flybys and be undetected. Organic compounds are the building blocks of life on Earth. Without them, life as we know it wouldn’t exist. If they are present in Enceladus’ oceans, they could be detected when Cassini passes through the plume on this encounter.

Perhaps more important, though, are the implications of finding hydrothermal activity somewhere other than Earth. It was once believed that all forms of life needed sunlight as a source of energy, but in 1977, the first hydrothermal vent -- essentially an underwater geyser of hot, mineral-rich water -- was discovered and it was teeming with life. The organisms were using the heat and minerals as a source of energy! Some scientists have hypothesized that hydrothermal vents could be where life on our planet first took hold and could represent environments in the solar system with the necessary ingredients to support life.

Teach It

Here are a handful of lessons and resources you can use to teach key concepts related to the October 28 Enceladus flyby and help your students feel connected to this exciting moment in science at Saturn.



  • NGSS 5-ESS2-1 - Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact.


Because scientists can’t dig beneath the ice and see what’s below, they rely on creating models that show what is happening beneath the surface. A model helps us imagine what can’t be seen and explains the things that we can see and measure. A model could be a drawing, a diagram or a computer simulation. For this model, students will draw a cut away model of Enceladus and iterate, or improve, their model as you provide more description, just as scientists improved their models as they learned more about Enceladus.

  1. Tell students there is a moon around Saturn. They should draw a moon (likely a circle, half-circle, or arc, depending on how big you want the drawing to be).

  2. Explain to students that the moon is covered in a shell of ice (students will need to modify their model by drawing a layer of ice). Thus far, everything students are modeling is observable by looking at the moon.

  3. Share with students that temperature measurements of the south pole revealed spots that are warmer than the rest of the moon’s surface. Ask students to brainstorm possible sources of heat at the south pole and explain what might happen to ice near a heat source. Based on this new information, and what they think might be causing the heat, allow them to modify their drawing. (Depending on what students brainstorm, their drawing might now include volcanoes, hot spots, magma, hydrothermal vents and a pool of liquid water beneath the ice).

  4. The next piece of information the students will need to incorporate into their drawing is that there are large cracks in the ice over the warmer south-pole region.

  5. Explain that students have now received images that show jets expelling material from the cracks. They will need to incorporate this new data and add it to their drawing.

  6. Tell students that by studying the gravity of the moon, scientists now believe there is an ocean covering the whole surface of the moon beneath the ice. Ask students to share how they would represent that in the model. Allow them to modify their drawing.

  7. Show students the following image depicting a model of Enceladus:

    Saturn's moon Enceladus global ocean model

    This model shows what scientists believe the interior of Enceladus may look like. Have students compare it to what they drew and note similarities and differences.

Particle Travel Rate


  • CCSS.MATH 6.RP.A.3.B - - Solve unit rate problems including those involving unit pricing and constant speed. For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?


Based on the size of the silica grains (6 to 9 nanometers), scientists think they spend anywhere from several months to a few years (a longer time than that means the grains would be larger) traveling from hydrothermal vents to space, a distance of 40 to 50 km.

  1. What rate (in km/day) are the particles traveling if it takes them 6 months to travel 50 km (assume 182 days)?

    50 km ÷ 182 days = 0.27 km/day

  2. What rate are they traveling if it takes two years to travel 40 km?

    40 km ÷ 730 days = 0.05 km/day

  3. Do you think the particles in each example traveled at the same speed the entire time they moved?

  4. Why might the particle rate vary?

  5. At what point in their journey might particles have been traveling at the highest rate?

Plume Data


  • CCSS.MATH 6.RP.A.3.B - Solve unit rate problems including those involving unit pricing and constant speed. For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?
  • CCSS.MATH 8.G.B.7 - Apply the Pythagorean Theorem to determine unknown side lengths in right triangles in real-world and mathematical problems in two and three dimensions.


Cassini will be flying past Enceladus at a staggering 8.5 km per second (19,014 mph). At an altitude of 49 km, the plume is estimated to be approximately 130 km across.

  • How long will Cassini have to capture particles and record data while within the plume?

    130 km ÷ 8.5 km/sec ≈ 15 seconds

  • If Cassini is 49 km above the surface of Enceladus at the center of the plume, what is its altitude as it enters and exits the plume (the radius of Enceladus is 252.1 km)?

    252.1 km + 49 km = 301.1 km
    (301.1 km)2 + (65 km)2 ≈ 95,000 km2
    √(95,000 km2) ≈ 308 km
    ≈ 308 km – 252.1 km ≈ 56 km

  • This information can help scientists determine where in the plume heavy particles may fall out if they are not detected on the edge of the plume but are detected closer to the middle of the plume. It is also important because the Cosmic Dust Analyzer uses a high-rate detector that can count impacting particles at over 10,000 parts per second to tell us how much material is being sprayed out.

Volume of Enceladus’ Ocean


  • CCSS.MATH 8.G.C.9 - Know the formulas for the volumes of cones, cylinders, and spheres and use them to solve real-world and mathematical problems.
  • CCSS.MATH HSG.GMD.A.3 - Use volume formulas for cylinders, pyramids, cones, and spheres to solve problems.


Gravity field measurements of Enceladus and the wobble in its orbital motion show a 10 km deep ocean beneath a layer of ice estimated to be between 30 km and 40 km thick. If the mean radius of Enceladus is 252.1 km, what is the minimum and maximum volume of water contained within its ocean?

Volume of a sphere = 43πr3

Minimum volume with a 40 km thick crust
43 π212.1 km3 - 43π202.1 km3 ≈ 40,000,000 km3 – 35,000,000 km3 ≈ 5,000,000 km3

Maximum volume with a 30 km thick crust
43 π222.1 km343 π212.1 km3 ≈ 46,000,000 km3 – 40,000,000 km3 ≈ 6,000,000 km3

This is important because if scientists know how much water is in the ocean and how much vapor is escaping through the plume, they can make estimates about how long the plume has existed -- or could continue to exist.

Download the Full Problem Set

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TAGS: Enceladus, moon, Saturn, Cassini, flyby, spacecraft, plume, jets, geysers, science, math

  • Lyle Tavernier

Animation showing sea level rise since January 1993

In the News

“Sea level rise” – we hear that phrase, but what does it mean, really? How does it affect us? Do I have to be concerned about it in my lifetime? These are all great questions!

Sea level rise is the increasing of the average global sea level. It doesn’t mean that seas are higher by the same amount everywhere. In fact, in some areas, such as the west coast of the US, sea level has actually dropped slightly … for now. But before we get into that, let’s understand the main contributors to sea level rise: 

  1. Melting mountain glaciers - Glaciers are bodies of ice on land that are constantly moving, carving paths through mountains and rock. As glaciers melt, the runoff flows into the oceans, raising their levels.
  2. Melting polar ice caps - Think of our north and south polar regions. At both locations, we have ice on land (“land ice”) and ice floating in the ocean (“sea ice”). Melting sea ice, much like ice cubes melting in a drink, does not affect the level of the oceans. Melting land ice, however, contributes to about one third of sea level rise.
  3. Thermal expansion of water - Consider that our oceans absorb over 90 percent of the heat trapped by greenhouse gasses in Earth’s atmosphere. When water heats up, its molecules become more energetic, causing the water to expand and take up more room, so that accounts for about a third of sea level rise.

Let’s take a closer look at global sea levels. Sea level is not constant everywhere. This is because it can be affected by ocean currents and natural cycles, such as the Pacific Decadal Oscillation, or PDO, a 20- to 30-year cyclical fluctuation in the Pacific Ocean’s surface temperature. Because of the PDO, right now the Eastern Pacific has higher sea levels than usual, while the Western Pacific has lower sea levels than usual. However, the global average of 3 millimeters of sea level rise per year is increasing and the rate that it’s increasing is speeding up. That means that sea level is rising, and it’s rising faster and faster. Take a look at this video for some great visuals and further explanation of how phenomena such as the Gulf Stream affect local sea level heights.

Why It's Important

You may be asking yourself, how do we know sea levels are rising? Well, a couple of ways. First, for the past 23 years we have been using data from several NASA satellites to constantly measure sea surface height around the globe. Data from these ocean altimeters is integrated to refine and calibrate measurements. Additionally, we have tide gauges on Earth to ground-truth (locally validate) our satellite measurements. As for historical data, we use sediment cores -- drillings into Earth that yield the oldest layers on the bottom and the youngest layers on top -- to examine where oceans once reached thousands of years ago.

Locally, folks are making observations – and already seeing the impacts of sea level rise on their communities. Places such as Miami are now experiencing regular flooding in downtown city streets at high tide. The South Pacific island nation of Kiribati saw a 2.6 millimeter rise in sea level between 1992 and 2010. That may not seem like much, but when you consider that the land only sits about 2 meters above sea level, that’s a big deal; some villages have already had to relocate to escape the rising tides. Residents of China's Yellow River delta are swamped by sea level rise of more than 25 centimeters (9 inches) a year. Even NASA is concerned about some of its facilities that are located in low-lying areas.

Besides wiping out dry land, encroaching salt water can pollute our fresh water supplies and damage fresh-water dependent ecosystems. It’s not just fresh water rivers and lakes that are at risk – our aquifers, or natural underground water storage, are at risk of filling with salt water as the ocean encroaches on the land above them.

Clearly, sea level rise is something that is already affecting people and will continue to do so. All three contributors to sea level rise can be attributed to the warming of the Earth system. Warming temperatures cause mountain glaciers and polar ice caps to melt, thereby increasing the volume of water in the oceans. At the same time, our oceans are getting warmer and expanding in volume as a result of this heat (thermal expansion). Since 1880, global sea level has risen 20 centimeters (8 inches); by 2100, it is projected to rise another 30 to 122 centimeters (1 to 4 feet). Watch this video for some illustrations of these facts:

Also check out the Climate Time Machine for Sea Level to see what impact a 1 meter to 6 meter rise in sea level will have on the coastal US and other areas of the world.

If we can control our contributions to the rise in greenhouse gases in Earth’s atmosphere, we can perhaps level out the warming of the Earth system and eventually stabilize our sea levels. In the meantime, we need to be prepared for the impact encroaching seas will have on our coastal communities and water supplies.

Teach It

To engage your students in analyzing real climate data and drawing their own conclusions, have them try these Next Generation Science Standards and Common Core Mathematics aligned problems.

> Download student worksheet (PDF)

Have students use these two satellite data graphs to answer the questions below. (To obtain exact data points, place your mouse on the section of the graph you would like to examine.)

  1. What is the source of the data for each graph?

  2. Which years are covered by each graph?

  3. Is one graph a better representation of global sea levels than the other? Why or why not?

  4. By approximately how many millimeters did sea level rise between:
    A) 1910 and 1930?
    55 mm – 45 mm = 10 mm (approx.)
    B) 1930 and 1950?
    120 mm – 55 mm = 65 mm (approx.)

  5. What is the approximate average rate of increase of sea level rise between 1870 and 2000?
    Note: students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find the slope of the line of best fit. The correct answer is approximately 1.5 mm per year.

  6. By how many millimeters did sea level rise between the first measurement obtained in January 1993 and the first measurement obtained in January 2013?
    (55.69)-(-16.56) = 72.25 mm

  7. What is the approximate rate of sea level rise between January 1993 and present?
    Note: The answer for this problem is directly stated at the top of the graph, 3.21 mm per year. Students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find slope of the line of best fit.
  8. Have students examine this line graph for average global temperature and use it to answer the questions below.

  9. By how much did the average global temperature change, and did it increase or decrease between 1910 and 1930? How about between 1930 and 1950?
    A) (-0.12)-(-0.46) = 0.34 (increase by 0.34 degrees C)
    B) (-0.19)-(-0.12) = -0.07 (decrease by 0.07 degrees C)

  10. Compare your answers to question number 8 with your answers to question number 4. Can you offer an explanation for the correlation or lack thereof?
    Encourage students to critically examine the graph, noting the temperature increase that occurred between 1930 and 1944, preceding the temperature decrease between 1944 and 1950. Students familiar with heat capacity should include this concept in their discussion.

  11. What is the approximate average global temperature rise per year from the first measurement taken in 1880 to present?
    Note: students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find slope of the line of best fit. The most conservative answer is 0.007°C per year, the best-fit answer is closer to 0.01°C.

Now, what can you do to be kind to Earth and do your part to control greenhouse gases in our atmosphere?

  • First, watch this video to learn more about our changing climate:

  • Next, check out this interactive feature to see what others around the globe are doing and add your ideas. 

Lesson Standards

CCSS-M 5.G.A.2 - Represent real world and mathematical problems by graphing points in the first quadrant of the coordinate plane, and interpret coordinate values of points in the context of the situation.

CCSS-M 7.RP.A.2.B - Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships.

CCSS-M HSF.IF.B.6 - Calculate and interpret the average rate of change of a function (presented symbolically or as a table) over a specified interval. Estimate the rate of change from a graph.

NGSS MS-ESS3-5 - Ask questions to clarify evidence of the factors that have caused the rise in global temperatures over the past century

NGSS MS-ESS3-3 - Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment

NGSS HS-ESS2-4 - Use a model to describe how variations in the flow of energy into and out of Earth’s systems result in changes in climate

NGSS HS-ESS3-5 - Analyze geoscience data and the results from global climate models to make an evidence-based forecast of the current rate of global or regional climate change and associated future impacts to Earth systems

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Images and Graphics


News and Resources

TAGS: Sea Level Rise, Climate Change, Global Warming, Earth Science

  • Ota Lutz