In the News
A full moon is always a good reason to go outside and turn your head toward the sky, but those who do so early on January 31 will be treated to the sight of a total lunar eclipse! It’s the only total lunar eclipse visible from North America in 2018, so it’s a great opportunity for students to observe the Moon – and for teachers to make connections to in-class science content.
How It works
Eclipses can occur when the Sun, the Moon and Earth align. Lunar eclipses can only happen during the full moon phase, when the Moon and the Sun are on opposite sides of Earth. At that point, the Moon could move into the shadow cast by Earth, resulting in a lunar eclipse. However, most of the time, the Moon’s slightly tilted orbit brings it above or below the shadow of Earth.
The time period when the Moon, Earth and the Sun are lined up and on the same plane – allowing for the Moon to pass through Earth’s shadow – is called an eclipse season. Eclipse seasons last about 34 days and occur just shy of every six months. When a full moon occurs during an eclipse season, the Moon travels through Earth’s shadow, creating a lunar eclipse.
Unlike solar eclipses, which require special glasses to view and can only be seen for a few short minutes in a very limited area, a total lunar eclipse can be seen for about an hour by anyone on the nighttime side of Earth – as long as skies are clear!
Why It’s Important
Lessons About the Moon
Explore our collection of standards-aligned lessons for grades 1-12.
Lunar eclipses have long played an important role in understanding Earth and its motions in space.
In ancient Greece, Aristotle noted that the shadows on the Moon during lunar eclipses were round, regardless of where an observer saw them. He realized that only if Earth were a spheroid would its shadows be round – a revelation that he and others had many centuries before the first ships sailed around the world.
Earth wobbles on its axis like a spinning top that’s about to fall over, a phenomenon called precession. Earth completes one wobble, or precession cycle, over the course of 26,000 years. Greek astronomer Hipparchus made this discovery by comparing the position of stars relative to the Sun during a lunar eclipse to those recorded hundreds of years earlier. A lunar eclipse allowed him to see the stars and know exactly where the Sun was for comparison – directly opposite the Moon. If Earth didn’t wobble, the stars would appear to be in the same place they were hundreds of years earlier. When Hipparchus saw that the stars’ positions had indeed moved, he knew that Earth must wobble on its axis!
Additionally, modern-day astronomers have used ancient eclipse records and compared them with computer simulations. These comparisons helped scientists determine the rate at which Earth’s rotation is slowing.
What to Expect
The Moon passes through two distinct parts of Earth’s shadow during a lunar eclipse. The outer part of the cone-shaped shadow is called the penumbra. The penumbra is less dark than the inner part of the shadow because it’s penetrated by some sunlight. (You have probably noticed that some shadows on the ground are darker than others, depending on how much outside light enters the shadow; the same is true for the outer part of Earth’s shadow). The inner part of the shadow, known as the umbra, is much darker because Earth blocks additional sunlight from entering the umbra.
At 2:51 a.m. PST on January 31, 2018, the edge of the Moon will begin entering the penumbra. The Moon will dim very slightly for the next 57 minutes as it moves deeper into the penumbra. Because this part of Earth’s shadow is not fully dark, you may only notice some dim shading (if anything at all) on the Moon near the end of this part of the eclipse. Should you decide to sleep in during this time, you won’t miss much.
At 3:48 a.m. PST, the edge of the Moon will begin entering the umbra. As the Moon moves into the darker shadow, significant darkening will be noticeable. Some say that during this part of the eclipse, the Moon looks as if it has had a bite taken out of it. That “bite” gets bigger and bigger as the Moon moves deeper into the shadow. If you will be on the East Coast of the United States, you might still be able to see the Moon just as it moves into the umbra before the Moon sets and the Sun rises.
At 4:51 a.m. PST, the Moon will be completely inside the umbra, marking the beginning of the total lunar eclipse. The moment of greatest eclipse, when the Moon is halfway through the umbra, occurs at 5:31 a.m. PST.
As the Moon moves completely into the umbra, something interesting happens: The Moon begins to turn reddish-orange. The reason for this phenomenon? Earth’s atmosphere. As sunlight passes through it, the small molecules that make up our atmosphere scatter blue light, which is why the sky appears blue. This leaves behind mostly red light that bends, or refracts, into Earth’s shadow. We can see the red light during an eclipse as it falls onto the Moon in Earth’s shadow. This same effect is what gives sunrises and sunsets a reddish-orange color.
A variety of factors affect the appearance of the Moon during a total lunar eclipse. Clouds, dust, ash, photochemical droplets and organic material in the atmosphere can change how much light is refracted into the umbra. Additionally, the January 2018 lunar eclipse takes place when the full moon is at or near the closest point in its orbit to Earth (popularly known as a supermoon). This means it is deeper inside the umbra shadow and therefore may appear darker. The potential for variation provides a great opportunity for students to observe and classify the lunar eclipse based on its brightness. Details can be found below in the “Teach It” section.
At 6:07 a.m. PST, the edge of the Moon will begin exiting the umbra and moving into the opposite side of the penumbra. This marks the end of the total lunar eclipse.
At 7:11 a.m. PST, the Moon will be completely outside of the umbra. It will continue moving out of the penumbra until the eclipse ends at 8:08 a.m.
Ask students to observe the lunar eclipse and evaluate the Moon’s brightness using the Danjon Scale of Lunar Eclipse Brightness. The Danjon scale illustrates the range of colors and brightness the Moon can take on during a total lunar eclipse and is a tool observers can use to characterize the appearance of an eclipse. View the lesson guide here. After the eclipse, have students compare and justify their evaluations of the eclipse.
Use these standards-aligned lessons and related activities to get your students excited about the eclipse, moon phases and Moon observations.
- *NEW* Evaluating a Lunar Eclipse (Grades 3-12) - Students use the Danjon Scale of Lunar Eclipse Brightness to illustrate the range of colors and brightness the Moon can take on during a total lunar eclipse.
- Observing the Moon (Grades K-6) - Students identify the Moon’s location in the sky and record their observations in a journal over the course of the moon-phase cycle.
- 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, 30-day, Moon cycle.
- Measuring the Supermoon (Grades 5-12) - Students take measurements of the Moon during its full phase over multiple Moon cycles to compare and contrast results.
- Modeling the Earth-Moon System (Grades 6-8) – Students learn about scale models and distance by creating a classroom-size Earth-Moon system.
- Make a Moon Phases Calendar and Calculator – Like a decoder wheel for the Moon, this calendar will show you where and when to see the Moon and every moon phase throughout the year!
- Try these related resources for students from NASA's Space Place:
- Lunar Eclipses and Solar Eclipses – This guide for kids provides an overview of lunar and solar eclipses.
- Why Does the Moon Have Craters? – Check out NASA's Space Place for the answer, written just for kids.
- NASA Moon Website – Find out more about the Moon and the NASA robots and humans who have visited it.
In the News
This month marks the 60th anniversary of the launch of America’s first satellite, Explorer 1. The small, pencil-shaped satellite did more than launch the U.S. into the Space Age. With its collection of instruments, or scientific tools, it turned space into not just a new frontier, but also a place of boundless scientific exploration that could eventually unveil secrets of new worlds – as well as the mysteries of our own planet.
How They Did It
At the height of competition for access to space, the U.S. and the Soviet Union were both building satellites that would ride atop rockets in a quest to orbit Earth. The Soviets launched Sputnik 1 on October 4, 1957. Shortly thereafter, on January 31, 1958, the U.S. launched Explorer 1, the satellite that would begin a new age of scientific space exploration.
Using rockets to do science from orbit was a brand-new option in the late 1950s. Before this time, rockets had only been used for military operations and atmospheric research. Still, rockets of that era weren’t very reliable and none had been powerful enough to place an object into Earth orbit.
Explore our collection of standards-aligned lessons for grades K-9.
In order to lift Explorer 1 to its destination in Earth orbit, an existing U.S. Army rocket, the Jupiter C, was fitted with a fourth stage, provided by the Jet Propulsion Laboratory in Pasadena, California. For this stage, a rocket motor was integrated into the satellite itself. The new, four-stage rocket was called “Juno 1.”
Prior to these first orbiting observatories, everything we knew about space and Earth came from Earth-based observation platforms – sensors and telescopes – and a few atmospheric sounding rockets. With the success of Explorer 1 and the subsequent development of more powerful rockets, we have been able to send satellites beyond Earth orbit to explore planets, moons, asteroids and even our Sun. With a space-based view of Earth, we are able to gain a global perspective and acquire a wide variety and amount of data at a rapid pace.
Why It’s Important
The primary science instrument on Explorer 1 was a cosmic ray detector designed to measure the radiation environment in Earth orbit – in part, to understand what hazards future spacecraft (or space-faring humans) might face. Once in space, this experiment, provided by James Van Allen of the University of Iowa, revealed a much lower cosmic ray count than expected. Van Allen theorized that the instrument might have been saturated by very strong radiation from a belt of charged particles trapped in space by Earth's magnetic field. The existence of the radiation belts was confirmed over the next few months by Explorer 3, Pioneer 3 and Explorer 4. The belts became known as the Van Allen radiation belts in honor of their discoverer.
Although we discovered and learned a bit about the Van Allen belts with the Explorer missions, they remain a source of scientific interest. The radiation belts are two (or more) donut-shaped regions encircling Earth, where high-energy particles, mostly electrons and ions, are trapped by Earth's magnetic field. The belts shrink and swell in size in response to incoming radiation from the Sun. They protect Earth from incoming high-energy particles, but this trapped radiation can affect the performance and reliability of our technologies, such as cellphone communication, and pose a threat to astronauts and spacecraft. It’s not safe to spend a lot of time inside the Van Allen radiation belts.
Most spacecraft are not designed to withstand high levels of particle radiation and wouldn’t last a day in the Van Allen belts. As a result, most spacecraft travel quickly through the belts toward their destinations, and non-essential instruments are turned off for protection during this brief time.
To conquer the challenge of extreme radiation in the belts while continuing the science begun by Explorer 1, NASA launched a pair of radiation-shielded satellites, the Van Allen Probes, in 2012. (The rocket that carried the Van Allen Probes into space was more than twice as tall as the rocket that carried Explorer 1 to orbit!)
The Van Allen Probes carry identical instruments and orbit Earth, following one another in highly elliptical, nearly identical orbits. These orbits bring the probes as close as about 300 miles (500 kilometers) above Earth’s surface, and take them as far out as about 19,420 miles (31,250 kilometers), traveling through diverse areas of the belts. By comparing observations from both spacecraft, scientists can distinguish between events that occur simultaneously throughout the belts, those that happen at only a single point in space, and those that move from one point to another over time.
The Van Allen Probes carry on the work begun by Explorer 1 and, like all successful space missions, are providing answers as well as provoking more questions. NASA continues to explore Earth and space using spacecraft launched aboard a variety of rockets designed to place these observatories in just the right spots to return data that will answer and inspire questions for years to come.
- *NEW* Build a Satellite (Grades 5-8) – Students will use the engineering design process to design, build, test and improve a model satellite intended to investigate the surface of a planet.
- Rocket Lessons and Activities (Grades K-9) – Use these exciting lessons to help your students experience the thrill of building their own rockets using the engineering design process!
- Earth Science Lessons and Activities (Grades K-12) – Use these lessons to engage your students in studying Earth from space!
- Build Your Own Space Mission – Have younger students play this game to place instruments aboard a spacecraft and launch it into space!
- Download the GLOBE Observer app and have students be citizen scientists in support of NASA Earth science missions! Learn more about how to participate.
In the Education Office at NASA’s Jet Propulsion Laboratory, we’re always working to bring exciting scientific content to K-12 classrooms. Educators can access many of these free resources, classroom materials and activities online, and we’re adding more all the time. The inspiration for these products often comes from the work being done at JPL and NASA, but sometimes it’s the teachers we work with whose creative ideas inspire the lessons we share with our community of STEM educators. Our new column, Teacher Feature, is an effort to capture those creative ideas and highlight the teachers behind them.
Featured Lesson: How to Read a Heat Map
Students learn to read, interpret and compare “heat maps” representing Earth science data.
LoriAnn Pawlik recently shared her NASA-inspired lesson during a professional development workshop hosted by the agency.
LoriAnn teaches STEM to grades K-5 at Penn Elementary School in Prince William County, Virginia, which focuses on students learning English, as well as those with learning disorders and autism. When she recently came across a lesson on the NASA/JPL Edu website, she saw an opportunity to bring real-world NASA data to her students.
How do you use NASA in the classroom?
Using the lesson “How to Read a Heat Map” as a jumping-off point, LoriAnn had her students first dive into the practice of reading and interpreting graphs. From here, she extended the lesson with an exploration of NASA satellites and the data they collect, focusing on the Gravity Recovery And Climate Experiment, or GRACE mission, to tie in with a community science night on water science.
GRACE was launched in 2002 to track changes in the distribution of liquid water, ice and land masses on Earth by measuring changes in the planet’s gravity field every 30 days. Circling Earth 16 times each day, GRACE spent more than 15 years collecting data – all of which is available online – before its science mission ended last October. The mission provided students the perfect context to study climate and water through authentic NASA data.
How did students react to the lesson?
LoriAnn set the stage for her students by explaining to them that they would be providing their data to NASA scientists.
“I told them that I was working on a project for a scientist from NASA-JPL and that we needed their help,” she said via email. “By the time I gave them the background and showed a brief GRACE video, they were all in – excited, eager enthusiastic! It helped that each table, or ‘engineering group,’ was responsible for a different U.S. state.”
As a result, students were able to plot the changes in gravitational fields for multiple locations over several years.
What are other ways you use NASA lessons or resources?
By extending the lesson, LoriAnn gave her students a sense of authentic ownership of the data and practice in real scientific analysis. But it wasn’t her first time uniting NASA science with her school curriculum:
“I'd been working with our second-graders on field studies of habitats,” LoriAnn explained. “We observed, journaled and tracked the migration of monarch butterflies, discussed what happened to habitats of living things since Hurricane Harvey and Hurricane Irma were just going through, and then I used the [NASA Mars Exploration website] to have students extend the findings to space habitats.”
Have a great idea for implementing NASA research in your class or looking to bring NASA science into your classroom? The Educator Professional Development Collaborative, or EPDC, can help. The EPDC at JPL serves educators in the greater Los Angeles area. Contact JPL education specialist Brandon Rodriguez at email@example.com. Note: Due to the popularity of EPDC programs, JPL may not be able to fulfill all requests.
Outside the Southern California area? The EPDC operates in all 50 states. Find an EPDC specialist near you.
The EPDC is managed by Texas State University as part of the NASA Office of Education. A free service for K-12 educators nationwide, the EPDC connects educators with the classroom tools and resources they need to foster students’ passion for careers in STEM and produce the next generation of scientists and engineers.
Looking for a stellar 2018 calendar? Try this new Moon Phases Calendar and Calculator DIY from the Education Office at NASA’s Jet Propulsion Laboratory!
Download the free, decoder-ring style calendar and assemble it to see when and where to view the Moon every day of the year. The calendar features daily moon phases, moonrise, moonset and overhead viewing times, a listing of Moon events including supermoons and lunar eclipses, plus graphics depicting the relative positions of Earth and the Moon during various moon phases. Use it to teach students about the phases of the Moon, for sky-gazing or simply as a unique wall calendar.
In the classroom, it makes a great addition to this Teachable Moment and related lessons about supermoons – two of which will ring in the new year in January 2018.
Explore these and more Moon-related lessons and activities from NASA/JPL Edu at the links below:
This week is Computer Science Education Week, an annual event meant to encourage and inspire K-12 students to explore computer programming. Students, teachers and curious learners of all ages are participating by using an hour of their week to create computer code as part of the Hour of Code initiative. Whether your students are experienced programmers or just learning the basics, this is a great opportunity to take part and get students engaged in computer science!
Try this lesson from NASA/JPL Edu to get involved and bring the excitement of NASA Mars exploration to students:
Explore Mars With Scratch
In this lesson, students learn about surface features on Mars, then use the visual programming language Scratch to create a Mars exploration game
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 new year. There will be two supermoons in a row in January 2018! Now is a great time to learn about these celestial events and get students exploring more about Earth’s only natural satellite.
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.
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
Make a Moon Phases Calendar
Use this Moon "decoder wheel" to see where and where to view the Moon all year!
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.
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.
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 phase over multiple Moon cycles to compare and contrast results.
- *NEW* Moon Phases Calendar and Calculator – Like a decoder wheel for the Moon, this calendar will show you where and when to see the Moon and every moon phase throughout the year!
- *NEW* Look at the Moon! Journaling Project – Draw what you see in a Moon Journal and see if you can predict the moon phase that comes next.
- 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.
- Learn more about the Moon on NASA's Moon website.
For the record: This story originally stated a supermoon would be visible in January and February 2018. The two supermoons of 2018 are both in January.
When Halloween rolls around at NASA’s Jet Propulsion Laboratory, we really let our nerd flags fly. Pumpkin carving contests turn into serious engineering design challenges and costume inspiration runs the gamut from real science to science fiction.
This year, join us in all our geekdom with these spooky (and educational!) space activities from the Education Office at NASA/JPL:
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.
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).
Creating a model that demonstrates gravitational waves traveling through spacetime is as simple as making a gelatin universe!
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.
- Gravitational waves news, videos and resources
- Laser Interferometer Gravitational-Wave Observatory (LIGO) Website
Update – Sept. 11, 2017: This feature (originally published on April 25, 2017) has been updated to reflect Cassini's current mission status, as well as new lessons and activities.
- Visit the Cassini website's Grand Finale Toolkit for a timeline, resources and more information about the final phase of the mission.
- Follow along with NASA via live stream during the Grand Finale on September 15 and in the days leading up to the event. Programming begins on September 13 at 10 a.m. PDT.
- Get the latest news and updates for the Cassini mission on the JPL News website.
- Explore these standards-aligned lessons and out-of-school activities to bring the wonder of NASA's Cassini mission and science at Saturn to students.
In the News
After almost 20 years in space, NASA's Cassini spacecraft has begun the final chapter of its remarkable story of exploration. This last phase of the mission has delivered unprecedented views of Saturn and taken Cassini where no spacecraft has been before – all the way between the planet and its rings. On Friday, Sept. 15 Cassini will perform its Grand Finale: a farewell dive into Saturn’s atmosphere to protect the environments of Saturn’s moons, including the potentially habitable Enceladus.
Lessons All About Saturn
Explore our collection of standards-aligned lessons about NASA's Cassini mission.
How It Works
On April 22, Cassini flew within 608 miles (979 km) of Saturn’s giant moon Titan, using the moon’s gravity to place the spacecraft on its path for the ring-gap orbits. Without this gravity assist from Titan, the daring, science-rich mission ending would not be possible.
Cassini is almost out of the propellant that fuels its main engine, which is used to make large course adjustments. A course adjustment requires energy. Because the spacecraft does not have enough rocket fuel on board, Cassini engineers have used an external energy source to set the spacecraft on its new trajectory: the gravity of Saturn’s moon Titan. (The engineers have often used Titan to make major shifts in Cassini’s flight plan.)
Titan is a massive moon and thus has a significant amount of gravity. As Cassini comes near Titan, the spacecraft is affected by this gravity – and can use it to its advantage. Often referred to as a “slingshot maneuver,” a gravity assist is a powerful tool, which uses the gravity of another body to speed up, slow down or otherwise alter the orbital path of a spacecraft.
When Cassini passed close by Titan on April 22, the moon’s gravity pulled strongly on the spacecraft. The flyby gave Cassini a change in velocity of about 1,800 mph (800 meters per second) that sent the spacecraft into its first of the ring-gap orbits on April 23. On April 26, Cassini made its first of 22 daring plunges between the planet and its mighty rings.
As Kepler’s third law indicates, Cassini traveled faster than ever before during these final smaller orbits. Cassini's orbit continued to cross the orbit of Titan during these ring-gap orbits. And every couple of orbits, Titan passed near enough to give the spacecraft a nudge. One last nudge occured on September 11, placing the spacecraft on its final, half-orbit, impact trajectory toward Saturn.
Because a few hardy microbes from Earth might have survived onboard Cassini all these years, NASA has chosen to safely dispose of the spacecraft in the atmosphere of Saturn to avoid the possibility of Cassini someday colliding with and contaminating moons such as Enceladus and Titan that may hold the potential for life. Cassini will continue to send back science measurements as long as it is able to transmit during its final dive into Saturn.
Why It’s Important
Flying closer than ever before to Saturn and its rings has provided an unprecedented opportunity for science. During these orbits, Cassini’s cameras have captured ultra-close images of the planet’s clouds and the mysterious north polar hexagon, helping us to learn more about Saturn’s atmosphere and turbulent storms.
The cameras have been taking high-resolution images of the rings, and to improve our knowledge of how much material is in the rings, Cassini has also been conducting gravitational measurements. Cassini's particle detectors have sampled icy ring particles being funneled into the atmosphere by Saturn's magnetic field. Data and images from these observations are helping bring us closer to understanding the origins of Saturn’s massive ring system.
Cassini has also been making detailed maps of Saturn's gravity and magnetic fields to reveal how the planet is structured internally, which could help solve the great mystery of just how fast Saturn is rotating.
On its first pass through the unexplored 1,500-mile-wide (2,400-kilometer) space between the rings and the planet, Cassini was oriented so that its high-gain antenna faced forward, shielding the delicate scientific instruments from potential impacts by ring particles. After this first ring crossing informed scientists about the low number of particles at that particular point in the gap, the spacecraft was oriented differently for the next four orbits, providing the science instruments unique observing angles. For ring crossings 6, 7 and 12, the spacecraft was again oriented so that its high-gain antenna faced forward.
Fittingly, Cassini's final moments will be spent doing what it does best, returning data on never-before-observed regions of the Saturnian system. On September 15, just hours before Cassini enters Saturn's atmosphere for its Grand Finale dive, it will collect and transmit its final images back to Earth. During its fateful dive, Cassini will be sending home new data in real time informing us about Saturn’s atmospheric composition. It's our last chance to gather intimate data about Saturn and its rings – until another spacecraft journeys to this distant planet.
Explore the many discoveries made by Cassini and the story of the mission on the Cassini website.
Use these standards-aligned lessons to get your students excited about the science we have learned and have yet to learn about the Saturnian system.
- NEW! Activity Collection: Jewel of the Solar System – Explore Saturn and the Cassini mission with this eight-part series of activities targeting after-school settings.
- Jewel of the Solar System Activity Guide
- What Do I See When I Picture Saturn?
- Where Are We in the Solar System?
- Discovering Saturn: The Real "Lord of the Rings"
- Saturn's Fascinating Features
- My Spacecraft to Saturn
- All About Titan and Huygens Probe
- Drop Zone! Design and Test a Probe
- Celebrating Saturn and Cassini
- Cassini Lessons for Educators
- Cassini Activities for Students
- Cassini Mission Website
- Cassini Grand Finale Toolkit
- Cassini Mission Overview
- Interactive Cassini Mission Timeline
- Video: NASA VR: Cassini's Grand Finale (360 Video)
- Slideshow for Students (includes a free poster!): 8 Real World Space Facts About Saturn's Moon Enceladus
- Slideshow for Students (includes a free poster!): Ocean Worlds
- Explore the Cassini Spacecraft in 3-D
- The Saturn System Through the Eyes of Cassini (e-book)