Cassini - Blog Posts

A Tour of Storms Across the Solar System

Earth is a dynamic and stormy planet with everything from brief, rumbling thunderstorms to enormous, raging hurricanes, which are some of the most powerful and destructive storms on our world. But other planets also have storm clouds, lightning — even rain, of sorts. Let’s take a tour of some of the unusual storms in our solar system and beyond.

Tune in May 22 at 3 p.m. for more solar system forecasting with NASA Chief Scientist Jim Green during the latest installment of NASA Science Live: https://www.nasa.gov/nasasciencelive.

1. At Mercury: A Chance of Morning Micrometeoroid Showers and Magnetic ‘Tornadoes’

Mercury, the planet nearest the Sun, is scorching hot, with daytime temperatures of more than 800 degrees Fahrenheit (about 450 degrees Celsius). It also has weak gravity — only about 38% of Earth's — making it hard for Mercury to hold on to an atmosphere.

Its barely there atmosphere means Mercury doesn’t have dramatic storms, but it does have a strange "weather" pattern of sorts: it’s blasted with micrometeoroids, or tiny dust particles, usually in the morning. It also has magnetic “tornadoes” — twisted bundles of magnetic fields that connect the planet’s magnetic field to space.

2. At Venus: Earth’s ‘Almost’ Twin is a Hot Mess

Venus is often called Earth's twin because the two planets are similar in size and structure. But Venus is the hottest planet in our solar system, roasting at more than 800 degrees Fahrenheit (430 degrees Celsius) under a suffocating blanket of sulfuric acid clouds and a crushing atmosphere. Add to that the fact that Venus has lightning, maybe even more than Earth. 

In visible light, Venus appears bright yellowish-white because of its clouds. Earlier this year, Japanese researchers found a giant streak-like structure in the clouds based on observations by the Akatsuki spacecraft orbiting Venus.

3. At Earth: Multiple Storm Hazards Likely

Earth has lots of storms, including thunderstorms, blizzards and tornadoes. Tornadoes can pack winds over 300 miles per hour (480 kilometers per hour) and can cause intense localized damage.

But no storms match hurricanes in size and scale of devastation. Hurricanes, also called typhoons or cyclones, can last for days and have strong winds extending outward for 675 miles (1,100 kilometers). They can annihilate coastal areas and cause damage far inland.

4. At Mars: Hazy with a Chance of Dust Storms

Mars is infamous for intense dust storms, including some that grow to encircle the planet. In 2018, a global dust storm blanketed NASA's record-setting Opportunity rover, ending the mission after 15 years on the surface.

Mars has a thin atmosphere of mostly carbon dioxide. To the human eye, the sky would appear hazy and reddish or butterscotch colored because of all the dust suspended in the air. 

5. At Jupiter: A Shrinking Icon

It’s one of the best-known storms in the solar system: Jupiter’s Great Red Spot. It’s raged for at least 300 years and was once big enough to swallow Earth with room to spare. But it’s been shrinking for a century and a half. Nobody knows for sure, but it's possible the Great Red Spot could eventually disappear.

6. At Saturn: A Storm Chasers Paradise

Saturn has one of the most extraordinary atmospheric features in the solar system: a hexagon-shaped cloud pattern at its north pole. The hexagon is a six-sided jet stream with 200-mile-per-hour winds (about 322 kilometers per hour). Each side is a bit wider than Earth and multiple Earths could fit inside. In the middle of the hexagon is what looks like a cosmic belly button, but it’s actually a huge vortex that looks like a hurricane.

Storm chasers would have a field day on Saturn. Part of the southern hemisphere was dubbed "Storm Alley" by scientists on NASA's Cassini mission because of the frequent storm activity the spacecraft observed there. 

7. At Titan: Methane Rain and Dust Storms

Earth isn’t the only world in our solar system with bodies of liquid on its surface. Saturn’s moon Titan has rivers, lakes and large seas. It’s the only other world with a cycle of liquids like Earth’s water cycle, with rain falling from clouds, flowing across the surface, filling lakes and seas and evaporating back into the sky. But on Titan, the rain, rivers and seas are made of methane instead of water.

Data from the Cassini spacecraft also revealed what appear to be giant dust storms in Titan’s equatorial regions, making Titan the third solar system body, in addition to Earth and Mars, where dust storms have been observed.

8. At Uranus: A Polar Storm

Scientists were trying to solve a puzzle about clouds on the ice giant planet: What were they made of? When Voyager 2 flew by in 1986, it spotted few clouds. (This was due in part to the thick haze that envelops the planet, as well as Voyager's cameras not being designed to peer through the haze in infrared light.) But in 2018, NASA’s Hubble Space Telescope snapped an image showing a vast, bright, stormy cloud cap across the north pole of Uranus.

9. At Neptune: Methane Clouds

Neptune is our solar system's windiest world. Winds whip clouds of frozen methane across the ice giant planet at speeds of more than 1,200 miles per hour (2,000 kilometers per hour) — about nine times faster than winds on Earth.

Neptune also has huge storm systems. In 1989, NASA’s Voyager 2 spotted two giant storms on Neptune as the spacecraft zipped by the planet. Scientists named the storms “The Great Dark Spot” and “Dark Spot 2.”

10. It’s Not Just Us: Extreme Weather in Another Solar System

Scientists using NASA’s Hubble Space Telescope made a global map of the glow from a turbulent planet outside our solar system. The observations show the exoplanet, called WASP-43b, is a world of extremes. It has winds that howl at the speed of sound, from a 3,000-degree-Fahrenheit (1,600-degree-Celsius) day side, to a pitch-black night side where temperatures plunge below 1,000 degrees Fahrenheit (500 degrees Celsius).

Discovered in 2011, WASP-43b is located 260 light-years away. The planet is too distant to be photographed, but astronomers detected it by observing dips in the light of its parent star as the planet passes in front of it.

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Greatest Hits — Craters We Love

Our solar system was built on impacts — some big, some small — some fast, some slow. This week, in honor of a possible newly-discovered large crater here on Earth, here’s a quick run through of some of the more intriguing impacts across our solar system.

1. Mercury: A Basin Bigger Than Texas

Mercury does not have a thick atmosphere to protect it from space debris. The small planet is riddled with craters, but none as spectacular as the Caloris Basin. “Basin” is what geologists call craters larger than about 186 miles (300 kilometers) in diameter. Caloris is about 950 miles (1,525 kilometers) across and is ringed by mile-high mountains.

For scale, the state of Texas is 773 miles (1,244 kilometers) wide from east to west.

2. Venus: Tough on Space Rocks

Venus’ ultra-thick atmosphere finishes off most meteors before they reach the surface. The planet’s volcanic history has erased many of its craters, but like almost any place with solid ground in our solar system, there are still impact scars to be found. Most of what we know of Venus’ craters comes from radar images provided by orbiting spacecraft, such as NASA’s Magellan.

Mead Crater is the largest known impact site on Venus. It is about 170 miles (275 kilometers) in diameter. The relatively-flat, brighter inner floor of the crater indicates it was filled with impact melt and/or lava.

3. Earth: Still Craters After All These Years

Evidence of really big impacts — such as Arizona’s Meteor Crater — are harder to find on Earth. The impact history of our home world has largely been erased by weather and water or buried under lava, rock or ice. Nonetheless, we still find new giant craters occasionally.

A NASA glaciologist has discovered a possible impact crater buried under more than a mile of ice in northwest Greenland.

This follows the finding, announced in November 2018, of a 19-mile (31-kilometer) wide crater beneath Hiawatha Glacier – the first meteorite impact crater ever discovered under Earth’s ice sheets. 

If the second crater, which has a width of over 22 miles (35 kilometers), is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.

4. Moon: Our Cratered Companion

Want to imagine what Earth might look like without its protective atmosphere, weather, water and other crater-erasing features? Look up at the Moon. The Moon’s pockmarked face offers what may be humanity’s most familiar view of impact craters.

One of the easiest to spot is Tycho, the tight circle and bright, radiating splat are easy slightly off center on the lower-left side of the full moon. Closer views of the 53-mile (85 kilometer)-wide crater from orbiting spacecraft reveal a beautiful central peak, topped with an intriguing boulder that would fill about half of a typical city block.

5. Mars: Still Taking Hits

Mars has just enough atmosphere to ensure nail-biting spacecraft landings, but not enough to prevent regular hits from falling space rocks. This dark splat on the Martian south pole is less than a year old, having formed between July and September 2018. The two-toned blast pattern tells a geologic story. The larger, lighter-colored blast pattern could be the result of scouring by winds from the impact shockwave on ice. The darker-colored inner blast pattern is because the impactor penetrated the thin ice layer, blasting the dark sand underneath in all directions.

6. Ceres: What Lies Beneath

The bright spots in Ceres’ Occator crater intrigued the world from the moment the approaching Dawn spacecraft first photographed it in 2015. Closer inspection from orbit revealed the spots to be the most visible example of hundreds of bright, salty deposits that decorate the dwarf planet like a smattering of diamonds. The science behind these bright spots is even more compelling: they are mainly sodium carbonate and ammonium chloride that somehow made their way to the surface in a slushy brine from within or below the crust. Thanks to Dawn, scientists have a better sense of how these reflective areas formed and changed over time — processes indicative of an active, evolving world.

7. Comet Tempel 1: We Did It!

Scientists have long known we can learn a lot from impact craters — so, in 2005, they made one themselves and watched it happen.

On July 4, 2005, NASA’s Deep Impact spacecraft trained its instruments on an 816-pound (370-kilogram) copper impactor as it smashed into comet Tempel 1.

One of the more surprising findings: The comet has a loose, “fluffy” structure, held together by gravity and contains a surprising amount of organic compounds that are part of the basic building blocks of life.

8. Mimas: May the 4th Be With You

Few Star Wars fans — us included — can resist Obi Wan Kenobi's memorable line “That’s no moon…” when images of Saturn’s moon Mimas pop up on a screen. Despite its Death Star-like appearance, Mimas is most definitely a moon. Our Cassini spacecraft checked, a lot — and the superlaser-looking depression is simply an 81-mile (130-kilometer) wide crater named for the moon’s discoverer, William Herschel.

9. Europa: Say What?

The Welsh name of this crater on Jupiter’s ocean moon Europa looks like a tongue-twister, but it is easiest pronounced as “pool.” Pwyll is thought to be one of the youngest features we know of on Europa. The bright splat from the impact extends more than 600 miles (about 1,000 kilometers) around the crater, a fresh blanket over rugged, older terrain. “Fresh,” or young, is a relative term in geology; the crater and its rays are likely millions of years old.

10. Show Us Your Greatest Hits

Got a passion for Stickney, the dominant bowl-shaped crater on one end of Mars’ moon Phobos? Or a fondness for the sponge-like abundance of impacts on Saturn’s battered moon Hyperion (pictured)? There are countless craters to choose from. Share your favorites with us on Twitter, Instagram and Facebook.

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Ultra-Close Orbits of Saturn = Ultra-Cool Science

On Sept. 15, 2017, our Cassini spacecraft ended its epic exploration of Saturn with a planned dive into the planet’s atmosphere–sending back new science to the very last second. The spacecraft is gone, but the science continues!

New research emerging from the final orbits represents a huge leap forward in our understanding of the Saturn system -- especially the mysterious, never-before-explored region between the planet and its rings. Some preconceived ideas are turning out to be wrong while new questions are being raised. How did they form? What holds them in place? What are they made of?

Six teams of researchers are publishing their work Oct. 5 in the journal Science, based on findings from Cassini's Grand Finale. That's when, as the spacecraft was running out of fuel, the mission team steered Cassini spectacularly close to Saturn in 22 orbits before deliberately vaporizing it in a final plunge into the atmosphere in September 2017.

Knowing Cassini's days were numbered, its mission team went for gold. The spacecraft flew where it was never designed to fly. For the first time, it probed Saturn's magnetized environment, flew through icy, rocky ring particles and sniffed the atmosphere in the 1,200-mile-wide (2,000-kilometer-wide) gap between the rings and the cloud tops. Not only did the engineering push the spacecraft to its limits, the new findings illustrate how powerful and agile the instruments were.

Many more Grand Finale science results are to come, but today's highlights include:

Complex organic compounds embedded in water nanograins rain down from Saturn's rings into its upper atmosphere. Scientists saw water and silicates, but they were surprised to see also methane, ammonia, carbon monoxide, nitrogen and carbon dioxide. The composition of organics is different from that found on moon Enceladus – and also different from those on moon Titan, meaning there are at least three distinct reservoirs of organic molecules in the Saturn system.

For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere. Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes -- a phenomenon known as "ring rain." But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it's all falling out of the rings faster than scientists thought -- as much as 10,000 kg of material per second.

Scientists were surprised to see what the material looks like in the gap between the rings and Saturn's atmosphere. They knew that the particles throughout the rings ranged from large to small. They thought material in the gap would look the same. But the sampling showed mostly tiny, nanograin- and micron-sized particles, like smoke, telling us that some yet-unknown process is grinding up particles. What could it be? Future research into the final bits of data sent by Cassini may hold the answer.

Saturn and its rings are even more interconnected than scientists thought. Cassini revealed a previously unknown electric current system that connects the rings to the top of Saturn's atmosphere.

Scientists discovered a new radiation belt around Saturn, close to the planet and composed of energetic particles. They found that while the belt actually intersects with the innermost ring, the ring is so tenuous that it doesn’t block the belt from forming.

Unlike every other planet with a magnetic field in our Solar System, Saturn's magnetic field is almost completely aligned with its spin axis. Think of the planet and the magnetic field as completely separate things that are both spinning. Both have the same center point, but they each have their own axis about which they spin. But for Saturn the two axes are essentially the same – no other planet does that, and we did not think it was even possible for this to happen. This new data shows a magnetic-field tilt of less than 0.0095 degrees. (Earth's magnetic field is tilted 11 degrees from its spin axis.) According to everything scientists know about how planetary magnetic fields are generated, Saturn should not have one. It's a mystery physicists will be working to solve.

Cassini flew above Saturn's magnetic poles, directly sampling regions where radio emissions are generated. The findings more than doubled the number of reported crossings of radio sources from the planet, one of the few non-terrestrial locations where scientists have been able to study a mechanism believed to operate throughout the universe. How are these signals generated? That’s still a mystery researchers are looking to uncover.

For the Cassini mission, the science rolling out from Grand Finale orbits confirms that the calculated risk of diving into the gap -- skimming the upper atmosphere and skirting the edge of the inner rings -- was worthwhile.

Almost everything going on in that region turned out to be a surprise, which was the importance of going there, to explore a place we'd never been before. And the expedition really paid off!

Analysis of Cassini data from the spacecraft’s instruments will be ongoing for years to come, helping to paint a clearer picture of Saturn.

To read the papers published in Science, visit: URL to papers

To learn more about the ground-breaking Cassini mission and its 13 years at Saturn, visit: https://www.nasa.gov/mission_pages/cassini/main/index.html

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10 Things: Why Cassini Mattered

One year ago, on Sept. 15, 2017, NASA’s Cassini spacecraft ended its epic exploration of Saturn with a planned dive into the planet’s atmosphere--sending back new science to the last second. The spacecraft is gone, but the science continues. Here are 10 reasons why Cassini mattered...

1. Game Changers

Cassini and ESA (European Space Agency)’s Huygens probe expanded our understanding of the kinds of worlds where life might exist.

2. A (Little) Like Home

At Saturn’s largest moon, Titan, Cassini and Huygens showed us one of the most Earth-like worlds we’ve ever encountered, with weather, climate and geology that provide new ways to understand our home planet.

3. A Time Machine (In a Sense)

Cassini gave us a portal to see the physical processes that likely shaped the development of our solar system, as well as planetary systems around other stars.

4. The Long Run

The length of Cassini’s mission enabled us to observe weather and seasonal changes over nearly half of a Saturn year, improving our understanding of similar processes at Earth, and potentially those at planets around other stars.

5. Big Science in Small Places

Cassini revealed Saturn’s moons to be unique worlds with their own stories to tell.

6. Ringscape

Cassini showed us the complexity of Saturn’s rings and the dramatic processes operating within them.

7. Pure Exploration

Some of Cassini’s best discoveries were serendipitous. What Cassini found at Saturn prompted scientists to rethink their understanding of the solar system.

8. The Right Tools for the Job

Cassini represented a staggering achievement of human and technical complexity, finding innovative ways to use the spacecraft and its instruments, and paving the way for future missions to explore our solar system.

9. Jewel of the Solar System

Cassini revealed the beauty of Saturn, its rings and moons, inspiring our sense of wonder and enriching our sense of place in the cosmos.

10. Much Still to Teach Us

The data returned by Cassini during its 13 years at Saturn will continue to be studied for decades, and many new discoveries are undoubtedly waiting to be revealed. To keep pace with what’s to come, we’ve created a new home for the mission--and its spectacular images--at https://solarsystem.nasa.gov/cassini.

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Spooky Sounds from Across the Solar System

Soaring to the depths of our universe, gallant spacecraft roam the cosmos, snapping images of celestial wonders. Some spacecraft have instruments capable of capturing radio emissions. When scientists convert these to sound waves, the results are eerie to hear.

In time for Halloween, we've put together a compilation of elusive "sounds" of howling planets and whistling helium that is sure to make your skin crawl.

Listen to a few here and visit our Soundcloud for more spooky sounds. 

Cassini Ring Crossing

This eerie audio represents data collected by our Cassini spacecraft, as it crossed through the gap between Saturn and its rings on April 26, 2017, during the first dive of the mission's Grand Finale. The instrument is able to record ring particles striking the spacecraft in its data. In the data from this dive, there is virtually no detectable peak in pops and cracks that represent ring particles striking the spacecraft. The lack of discernible pops and cracks indicates the region is largely free of small particles. 

Voyager Tsunami Waves in Interstellar Space 

Listen to this howling audio from our Voyager 1 spacecraft. Voyager 1 has experienced three "tsunami waves" in interstellar space. This kind of wave occurs as a result of a coronal mass ejection erupting from the Sun. The most recent tsunami wave that Voyager experienced began in February 2014, and may still be going. Listen to how these waves cause surrounding ionized matter to ring like a bell.

Voyager Sounds of Interstellar Space

Our Voyager 1 spacecraft captured these high-pitched, spooky sounds of interstellar space from October to November 2012 and April to May 2013.

The soundtrack reproduces the amplitude and frequency of the plasma waves as "heard" by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.

When scientists extrapolated this line even further back in time (not shown), they deduced that Voyager 1 first encountered interstellar plasma in August 2012.

Plasma Sounds at Jupiter

Ominous sounds of plasma! Our Juno spacecraft has observed plasma wave signals from Jupiter’s ionosphere. The results in this video show an increasing plasma density as Juno descended into Jupiter’s ionosphere during its close pass by Jupiter on February 2, 2017.  

Roar of Jupiter

Juno's Waves instrument recorded this supernatural sounding encounter with the bow shock over the course of about two hours on June 24, 2016. "Bow shock" is where the supersonic solar wind is heated and slowed by Jupiter's magnetosphere. It is analogous to a sonic boom on Earth. The next day, June 25, 2016, the Waves instrument witnessed the crossing of the magnetopause. "Trapped continuum radiation" refers to waves trapped in a low-density cavity in Jupiter's magnetosphere.

Visit the NASA Soundcloud for more spooky space sounds: https://soundcloud.com/nasa/sets/spookyspacesounds

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Solar System: 10 Things to Know This Week

Need some space? 

Here are 10 perspective-building images for your computer desktop and mobile device wallpaper. 

These are all real images, sent very recently by our planetary missions throughout the solar system. 

1. Our Sun

Warm up with this view from our Solar Dynamics Observatory showing active regions on the Sun in October 2017. They were observed in a wavelength of extreme ultraviolet light that reveals plasma heated to over a million degrees. 

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2. Jupiter Up-Close

This series of enhanced-color images shows Jupiter up close and personal, as our Juno spacecraft performed its eighth flyby of the gas giant planet on Sept. 1, 2017. 

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3. Saturn’s and Its Rings

With this mosaic from Oct. 28, 2016, our Cassini spacecraft captured one of its last looks at Saturn and its main rings from a distance. 

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4. Gale Crater on Mars

This look from our Curiosity Mars rover includes several geological layers in Gale crater to be examined by the mission, as well as the higher reaches of Mount Sharp beyond. The redder rocks of the foreground are part of the Murray formation. Pale gray rocks in the middle distance of the right half of the image are in the Clay Unit. A band between those terrains is "Vera Rubin Ridge," where the rover is working currently. The view combines six images taken with the rover's Mast Camera (Mastcam) on Jan. 24, 2017. 

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5. Sliver of Saturn

Cassini peers toward a sliver of Saturn's sunlit atmosphere while the icy rings stretch across the foreground as a dark band on March 31, 2017. This view looks toward the unilluminated side of the rings from about 7 degrees below the ring plane. 

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6. Dwarf Planet Ceres 

This image of the limb of dwarf planet Ceres shows a section of the northern hemisphere, as seen by our Dawn mission. Prominently featured is Occator Crater, home of Ceres' intriguing "bright spots." The latest research suggests that the bright material in this crater is comprised of salts left behind after a briny liquid emerged from below. 

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7. Martian Crater

This image from our Mars Reconnaissance Orbiter (MRO) shows a crater in the region with the most impressive known gully activity in Mars' northern hemisphere. Gullies are active in the winter due to carbon dioxide frost, but northern winters are shorter and warmer than southern winters, so there is less frost and less gully activity. 

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8. Dynamic Storm on Jupiter

A dynamic storm at the southern edge of Jupiter's northern polar region dominates this Jovian cloudscape, courtesy of Juno. This storm is a long-lived anticyclonic oval named North North Temperate Little Red Spot 1. Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager. 

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9. Rings Beyond Saturn’s Sunlit Horizon 

This false-color view from the Cassini spacecraft gazes toward the rings beyond Saturn's sunlit horizon. Along the limb (the planet's edge) at left can be seen a thin, detached haze. 

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10. Saturn’s Ocean-Bearing Moon Enceladus

Saturn's active, ocean-bearing moon Enceladus sinks behind the giant planet in a farewell portrait from Cassini. This view of Enceladus was taken by NASA's Cassini spacecraft on Sept. 13, 2017. It is among the last images Cassini sent back before its mission came to an end on Sept. 15, after nearly 20 years in space. 

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Applying Wallpaper: 1. Click on the screen resolution you would like to use. 2. Right-click on the image (control-click on a Mac) and select the option 'Set the Background' or 'Set as Wallpaper' (or similar).

Places to look for more of our pictures include solarsystem.nasa.gov/galleries, images.nasa.gov and www.jpl.nasa.gov/spaceimages.

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Cassini Mission: What’s Next?

It’s Friday, Sept. 15 and our Cassini mission has officially come to a spectacular end. The final signal from the spacecraft was received here on Earth at 7:55 a.m. EDT after a fateful plunge into Saturn’s atmosphere.

After losing contact with Earth, the spacecraft burned up like a meteor, becoming part of the planet itself.

Although bittersweet, Cassini’s triumphant end is the culmination of a nearly 20-year mission that overflowed with discoveries.

But, what happens now?

Mission Team and Data

Now that the spacecraft is gone, most of the team’s engineers are migrating to other planetary missions, where they will continue to contribute to the work we’re doing to explore our solar system and beyond.

Mission scientists will keep working for the coming years to ensure that we fully understand all of the data acquired during the mission’s Grand Finale. They will carefully calibrate and study all of this data so that it can be entered into the Planetary Data System. From there, it will be accessible to future scientists for years to come.

Even beyond that, the science data will continue to be worked on for decades, possibly more, depending on the research grants that are acquired.

Other team members, some who have spent most of their career working on the Cassini mission, will use this as an opportunity to retire.

Future Missions

In revealing that Enceladus has essentially all the ingredients needed for life, the mission energized a pivot to the exploration of “ocean worlds” that has been sweeping planetary science over the past couple of decades.

Jupiter’s moon Europa has been a prime target for future exploration, and many lessons during Cassini’s mission are being applied in planning our Europa Clipper mission, planned for launch in the 2020s.

The mission will orbit the giant planet, Jupiter, using gravitational assists from large moons to maneuver the spacecraft into repeated close encounters, much as Cassini has used the gravity of Titan to continually shape the spacecraft’s course.

In addition, many engineers and scientists from Cassini are serving on the new Europa Clipper mission and helping to shape its science investigations. For example, several members of the Cassini Ion and Neutral Mass Spectrometer team are developing an extremely sensitive, next-generation version of their instrument for flight on Europa Clipper. What Cassini has learned about flying through the plume of material spraying from Enceladus will be invaluable to Europa Clipper, should plume activity be confirmed on Europa.

In the decades following Cassini, scientists hope to return to the Saturn system to follow up on the mission's many discoveries. Mission concepts under consideration include robotic explorers to drift on the methane seas of Titan and fly through the Enceladus plume to collect and analyze samples for signs of biology.

Atmospheric probes to all four of the outer planets have long been a priority for the science community, and the most recent recommendations from a group of planetary scientists shows interest in sending such a mission to Saturn. By directly sampling Saturn's upper atmosphere during its last orbits and final plunge, Cassini is laying the groundwork for an potential Saturn atmospheric probe.

A variety of potential mission concepts are discussed in a recently completed study — including orbiters, flybys and probes that would dive into Uranus' atmosphere to study its composition. Future missions to the ice giants might explore those worlds using an approach similar to Cassini's mission.

Learn more about the Cassini mission and its Grand Finale HERE.

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Cassini Spacecraft: Top Discoveries

Our Cassini spacecraft has been exploring Saturn, its stunning rings and its strange and beautiful moons for more than a decade.

Having expended almost every bit of the rocket propellant it carried to Saturn, operators are deliberately plunging Cassini into the planet to ensure Saturn’s moons will remain pristine for future exploration – in particular, the ice-covered, ocean-bearing moon Enceladus, but also Titan, with its intriguing pre-biotic chemistry.

Let’s take a look back at some of Cassini’s top discoveries:  

Titan

Under its shroud of haze, Saturn’s planet-sized moon Titan hides dunes, mountains of water ice and rivers and seas of liquid methane. Of the hundreds of moons in our solar system, Titan is the only one with a dense atmosphere and large liquid reservoirs on its surface, making it in some ways more like a terrestrial planet.

Both Earth and Titan have nitrogen-dominated atmospheres – over 95% nitrogen in Titan’s case. However, unlike Earth, Titan has very little oxygen; the rest of the atmosphere is mostly methane and traced amounts of other gases, including ethane.

There are three large seas, all located close to the moon’s north pole, surrounded by numerous smaller lakes in the northern hemisphere. Just one large lake has been found in the southern hemisphere.

Enceladus

The moon Enceladus conceals a global ocean of salty liquid water beneath its icy surface. Some of that water even shoots out into space, creating an immense plume!

For decades, scientists didn’t know why Enceladus was the brightest world in the solar system, or how it related to Saturn’s E ring. Cassini found that both the fresh coating on its surface, and icy material in the E ring originate from vents connected to a global subsurface saltwater ocean that might host hydrothermal vents.

With its global ocean, unique chemistry and internal heat, Enceladus has become a promising lead in our search for worlds where life could exist.

Iapetus

Saturn’s two-toned moon Iapetus gets its odd coloring from reddish dust in its orbital path that is swept up and lands on the leading face of the moon.

The most unique, and perhaps most remarkable feature discovered on Iapetus in Cassini images is a topographic ridge that coincides almost exactly with the geographic equator. The physical origin of the ridge has yet to be explained...

It is not yet year whether the ridge is a mountain belt that has folded upward, or an extensional crack in the surface through which material from inside Iapetus erupted onto the surface and accumulated locally.

Saturn’s Rings

Saturn’s rings are made of countless particles of ice and dust, which Saturn’s moons push and tug, creating gaps and waves.

Scientists have never before studied the size, temperature, composition and distribution of Saturn’s rings from Saturn obit. Cassini has captured extraordinary ring-moon interactions, observed the lowest ring-temperature ever recorded at Saturn, discovered that the moon Enceladus is the source for Saturn’s E ring, and viewed the rings at equinox when sunlight strikes the rings edge-on, revealing never-before-seen ring features and details.

Cassini also studied features in Saturn’s rings called “spokes,” which can be longer than the diameter of Earth. Scientists think they’re made of thin icy particles that are lifted by an electrostatic charge and only last a few hours.  

Auroras

The powerful magnetic field that permeates Saturn is strange because it lines up with the planet’s poles. But just like Earth’s field, it all creates shimmering auroras.

Auroras on Saturn occur in a process similar to Earth’s northern and southern lights. Particles from the solar wind are channeled by Saturn’s magnetic field toward the planet’s poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light.  

Turbulent Atmosphere

Saturn’s turbulent atmosphere churns with immense storms and a striking, six-sided jet stream near its north pole.

Saturn’s north and south poles are also each beautifully (and violently) decorated by a colossal swirling storm. Cassini got an up-close look at the north polar storm and scientists found that the storm’s eye was about 50 times wider than an Earth hurricane’s eye.

Unlike the Earth hurricanes that are driven by warm ocean waters, Saturn’s polar vortexes aren’t actually hurricanes. They’re hurricane-like though, and even contain lightning. Cassini’s instruments have ‘heard’ lightning ever since entering Saturn orbit in 2004, in the form of radio waves. But it wasn’t until 2009 that Cassini’s cameras captured images of Saturnian lighting for the first time.

Cassini scientists assembled a short video of it, the first video of lightning discharging on a planet other than Earth.

Cassini’s adventure will end soon because it’s almost out of fuel. So to avoid possibly ever contaminating moons like Enceladus or Titan, on Sept. 15 it will intentionally dive into Saturn’s atmosphere.

The spacecraft is expected to lose radio contact with Earth within about one to two minutes after beginning its decent into Saturn’s upper atmosphere. But on the way down, before contact is lost, eight of Cassini’s 12 science instruments will be operating! More details on the spacecraft’s final decent can be found HERE.

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After 20 years in space, the Cassini spacecraft is running out of fuel. In 2010, Cassini began a seven-year mission extension in which the plan was to expend all of the spacecraft’s propellant exploring Saturn and its moons. This led to the Grand Finale and ends with a plunge into the planet’s atmosphere at 6:32 a.m. EDT on Friday, Sept. 15.

The spacecraft will ram through Saturn’s atmosphere at four times the speed of a re-entry vehicle entering Earth’s atmosphere, and Cassini has no heat shield. So temperatures around the spacecraft will increase by 30-to-100 times per minute, and every component of the spacecraft will disintegrate over the next couple of minutes…

Cassini’s gold-colored multi-layer insulation blankets will char and break apart, and then the spacecraft's carbon fiber epoxy structures, such as the 11-foot (3-meter) wide high-gain antenna and the 30-foot (11-meter) long magnetometer boom, will weaken and break apart. Components mounted on the outside of the central body of the spacecraft will then break apart, followed by the leading face of the spacecraft itself.

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Our Cassini spacecraft has been traveling in space for almost 20 years, exploring Saturn, its rings and even some of its moons. This mission has revealed never-before-seen events that are changing our understanding of how planetary systems form and what conditions might lead to habitats for life.

Cassini will complete its remarkable story of exploration with an intentional plunge into Saturn’s atmosphere, ending its mission.  

Participate in our Grand Finale Events

Wednesday, Sept. 13

1 p.m. EDT – News Conference from our Jet Propulsion Laboratory with a detailed preview of final mission activities Watch HERE.

Thursday, Sept 14

4:00 - 5:00 p.m. EDT - NASA Social Live Broadcast with mission experts Watch HERE.

Friday, Sept. 15

7:00 – 8:30 a.m. EDT – Live commentary on NASA TV and online of the spacecraft’s final dive into Saturn’s atmosphere. Watch HERE.

Around 8:00 a.m. EDT – Expected time of last signal and science data from Cassini Watch HERE.

9:30 a.m. EDT – Post-mission news conference Watch HERE.

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Solar System: Things to Know This Week

Almost every day, we receive a message from a spacecraft more than 10.6 billion miles (about 17 billion km) away.

At that unimaginable distance, it takes the radio signal almost 16 hours to arrive. The spacecraft is Voyager 2, which launched 40 years ago this month. It's still operating, sending back dispatches from the dark reaches well beyond the orbit of Pluto. Even now, scientists are still actively exploring the outer boundaries of the solar system using Voyager 2, decades after its "Grand Tour" of the giant planets Jupiter, Saturn, Uranus and Neptune revealed their splendors like never before. This week, we recall 10 highlights from one of the most epic voyages in human history.

1. A Journey of 10 Billion Miles Begins With the First Step

Voyager 2 set out from Earth on Aug. 20, 1977. Even though it launched before its twin spacecraft, Voyager 1, it carried the '2' moniker because mission planners knew its trajectory would bring it to Jupiter after Voyager 1's arrival there.

2. The Grand Tour

Voyager 2's trajectory was special because it took advantage of a rare orbital alignment to fly by all four gas giant planets: Jupiter, Saturn, Uranus and Neptune. It was the first, and so far the only, spacecraft to carry out a close-up reconnaissance of Uranus and Neptune.

3. Not-So-Gentle Giant

Voyager 2 flew by Jupiter in April 1979, capturing striking images of the planet's volcanic moon Io and its violent storms larger than the entire Earth.

4. Saturn's Not the Only One

Jupiter has its own ring system, and Voyager 2 provided the first pictures.

5. An Ocean Under Ice

During its Jupiter encounter, Voyager 2 obtained close-up looks at Jupiter's moon Europa, including linear cracks and other features which first led scientists to realize Europa probably hides a vast sea of liquid water beneath an icy shell, the first known world outside Earth that could have an ocean.

6. Ringworld, the Prequel

Voyager 2 zoomed through the Saturn system in August 1981. It saw hints of mysterious features that the Cassini mission would later reveal in stunning detail, including Enceladus, with its bright surface that suggested geologic activity, and Saturn's intriguing hexagonal jet stream.

7. Swiftly by a Tilted Planet

In January 1984, Voyager offered humanity its first detailed look at the seventh planet, Uranus, the only one tilted on its side relative to the Sun. Voyager images revealed 11 new moons, including Juliet, Puck, Cressida, Rosalind and Ophelia. The moon Miranda presented a bizarre landscape that left scientists debating its origins for years. Voyager also captured views of the planet's lacy rings, and found that it is the coldest in the solar system, at minus 353 degrees Fahrenheit (59 Kelvin).

8. In Neptune's Blue Realm

After picking up a gravitational speed boost at each previous planetary encounter, by the time Voyager reached Neptune it shot through the entire system of Neptunian rings and moons in a matter of hours. Voyager saw a titanic storm in Neptune's windy atmosphere, discovered new moons, and revealed active geysers erupting on Triton's frigid surface.

9. Postcards From the Edge

Although their cameras are no longer functioning, other key scientific instruments on board both Voyager spacecraft are still collecting data. Voyager 1 is exploring the boundary between the Sun's realm and interstellar space. Voyager 2 hasn't traveled quite as far. In September 2007, it crossed the termination shock (where the speed of the solar wind of charged particles drops below the speed of sound) at a point about 84 Astronomical Units from the Sun (more than twice the distance to Pluto). See https://go.nasa.gov/2uwrndb

10. Ride Along

Voyager's mission is far from over. Engineers estimate the spacecraft will have enough power to operate into the mid-2020s. You can ride along at www.jpl.nasa.gov/voyager, or by following @NASAVoyager on Twitter and by downloading our free 3-D space simulation software, Eyes on the Solar System at eyes.nasa.gov.

One more thing: Inspired by the messages of goodwill carried on Voyager's Golden Record, you're invited to send a short, uplifting message to Voyager and all that lies beyond it via social media. With input from the Voyager team and a public vote, one of these messages will be selected for us to beam into interstellar space on Sept. 5, 2017—the 40th anniversary of Voyager 1's launch. Post your message on social media with the tag #MessageToVoyager by Aug 15. Details: www.jpl.nasa.gov/voyager/message/

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Magnetospheres: How Do They Work?

The sun, Earth, and many other planets are surrounded by giant magnetic bubbles.

Space may seem empty, but it’s actually a dynamic place, dominated by invisible forces, including those created by magnetic fields.  Magnetospheres – the areas around planets and stars dominated by their magnetic fields – are found throughout our solar system. They deflect high-energy, charged particles called cosmic rays that are mostly spewed out by the sun, but can also come from interstellar space. Along with atmospheres, they help protect the planets’ surfaces from this harmful radiation.

It’s possible that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, so finding magnetospheres around other planets is a big step toward determining if they could support life.

But not all magnetospheres are created equal – even in our own backyard, not all planets in our solar system have a magnetic field, and the ones we have observed are all surprisingly different.

Earth’s magnetosphere is created by the constantly moving molten metal inside Earth. This invisible “force field” around our planet has an ice cream cone-like shape, with a rounded front and a long, trailing tail that faces away from the sun. The magnetosphere is shaped that way because of the constant pressure from the solar wind and magnetic fields on the sun-facing side.

Earth’s magnetosphere deflects most charged particles away from our planet – but some do become trapped in the magnetic field and create auroras when they rain down into the atmosphere.

We have several missions that study Earth’s magnetosphere – including the Magnetospheric Multiscale mission, Van Allen Probes, and Time History of Events and Macroscale Interactions during Substorms (also known as THEMIS) – along with a host of other satellites that study other aspects of the sun-Earth connection.

Mercury, with a substantial iron-rich core, has a magnetic field that is only about 1% as strong as Earth’s. It is thought that the planet’s magnetosphere is stifled by the intense solar wind, limiting its strength, although even without this effect, it still would not be as strong as Earth’s. The MESSENGER satellite orbited Mercury from 2011 to 2015, helping us understand our tiny terrestrial neighbor.

After the sun, Jupiter has by far the biggest magnetosphere in our solar system – it stretches about 12 million miles from east to west, almost 15 times the width of the sun. (Earth’s, on the other hand, could easily fit inside the sun.) Jupiter does not have a molten metal core like Earth; instead, its magnetic field is created by a core of compressed liquid metallic hydrogen.

One of Jupiter’s moons, Io, has intense volcanic activity that spews particles into Jupiter’s magnetosphere. These particles create intense radiation belts and the large auroras around Jupiter’s poles.

Ganymede, Jupiter’s largest moon, also has its own magnetic field and magnetosphere – making it the only moon with one. Its weak field, nestled in Jupiter’s enormous shell, scarcely ruffles the planet’s magnetic field.

Our Juno mission orbits inside the Jovian magnetosphere sending back observations so we can better understand this region. Previous observations have been received from Pioneers 10 and 11, Voyagers 1 and 2, Ulysses, Galileo and Cassini in their flybys and orbits around Jupiter.

Saturn’s moon Enceladus transforms the shape of its magnetosphere. Active geysers on the moon’s south pole eject oxygen and water molecules into the space around the planet. These particles, much like Io’s volcanic emissions at Jupiter, generate the auroras around the planet’s poles. Our Cassini mission studies Saturn’s magnetic field and auroras, as well as its moon Enceladus.

Uranus’ magnetosphere wasn't discovered until 1986 when data from Voyager 2’s flyby revealed weak, variable radio emissions. Uranus’ magnetic field and rotation axis are out of alignment by 59 degrees, unlike Earth’s, whose magnetic field and rotation axis differ by only 11 degrees. On top of that, the magnetic field axis does not go through the center of the planet, so the strength of the magnetic field varies dramatically across the surface. This misalignment also means that Uranus’ magnetotail – the part of the magnetosphere that trails away from the sun – is twisted into a long corkscrew.

Neptune’s magnetosphere is also tilted from its rotation axis, but only by 47. Just like on Uranus, Neptune’s magnetic field strength varies across the planet. This also means that auroras can be seen away from the planet’s poles – not just at high latitudes, like on Earth, Jupiter and Saturn.

Does Every Planet Have a Magnetosphere?

Neither Venus nor Mars have global magnetic fields, although the interaction of the solar wind with their atmospheres does produce what scientists call an “induced magnetosphere.” Around these planets, the atmosphere deflects the solar wind particles, causing the solar wind’s magnetic field to wrap around the planet in a shape similar to Earth’s magnetosphere.

What About Beyond Our Solar System?

Outside of our solar system, auroras, which indicate the presence of a magnetosphere, have been spotted on brown dwarfs – objects that are bigger than planets but smaller than stars.

There’s also evidence to suggest that some giant exoplanets have magnetospheres. As scientists now believe that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, finding magnetospheres around exoplanets is a big step in finding habitable worlds.  

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Solar System: Things to Know This Week

We've been up close and personal with Saturn for 13 years now, thanks to the Cassini mission. 

From a tour of Saturn's many enthralling moons to an incredible view of Earth through its rings, the planet continues to captivate the imagination. This week, here are 10 things you need to know about our fascinating ringed neighbor.

1. Strange Sighting

When Galileo Galilei was observing Saturn in the 1600s, he noticed strange objects on each side of the planet. He drew in his notes a triple-bodied planet system with ears. These "ears" were later discovered to be the rings of Saturn.

2. Solar System Status

Saturn orbits our sun and is the sixth planet from the sun at an average distance of about 886 million miles or 9.5 AU.

3. Short Days

Time flies when you're on Saturn. One day on Saturn takes just 10.7 hours (the time it takes for Saturn to rotate or spin once). The planet makes a complete orbit around the sun (a year in Saturnian time) in 29 Earth years, or 10,756 Earth days. saturn.jpl.nasa.gov/news/2955/measuring-a-day

4. No Shoes Necessary

That's because you can't stand on Saturn—it's a gas-giant planet and doesn't have a solid surface. But you might want a jacket. The planet's temperatures can dip to -220 degrees F.

5. Few visitors

Only a handful of missions have made their way to Saturn: Pioneer 11, Voyager 1 and 2, and Cassini-Huygens, which is there now. Since 2004, Cassini has been exploring Saturn and its moons and rings—but will complete its journey on Sept. 15, 2017.

6. Saturn's Close-Up

This month is a great time to observe Saturn from Earth. Check out June's "What's Up?" video for a how-to guide.

7. Daring Dives

Saturn's spectacular ring system is made up of seven rings with several gaps and divisions between them. From now until September, the Cassini spacecraft is performing a set of daring dives every week between the planet and the rings. No other mission has ever explored this unique region before, and what we learn from these final orbits will help us understand of how giant planets—and planetary systems everywhere—form and evolve.

8. Many, Many Moons 

Saturn has a total of 62 moons: 53 known moons, with an additional nine moons awaiting confirmation.

9. Curious Shapes 

Saturn's moon Atlas looks like a flying saucer. See for yourself.

10. Would You Live on a Moon? 

Saturn can't support life as we know it, but some of its moons have conditions that might support life. Ocean worlds could be the answer to life in space and two of Saturn's moons—Titan and Enceladus—are on that list.

Want to learn more? Read our full list of the 10 things to know this week about the solar system HERE.

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Solar System: Things to Know This Week

With only four months left in the mission, Cassini is busy at Saturn. The upcoming cargo launch, anniversaries and more!

As our Cassini spacecraft made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. Credits: NASA/JPL-Caltech/Space Science Institute/Hampton University

1-3. The Grand Finale

Our Cassini spacecraft has begun its final mission at Saturn. Some dates to note:

May 28, 2017: Cassini makes its riskiest ring crossing as it ventures deeper into Saturn's innermost ring (D ring).

June 29, 2017: On this day in 2004, the Cassini orbiter and its travel companion the European Space Agency's Huygens probe arrived at Saturn.

September 15, 2017: In a final, spectacular dive, Cassini will plunge into Saturn - beaming science data about Saturn's atmosphere back to Earth to the last second. It's all over at 5:08 a.m. PDT.

More about the Grand Finale

4. Cargo Launch to the International Space Station

June 1, 2017: Target date of the cargo launch. The uncrewed Dragon spacecraft will launch on a Falcon 9 from Launch Complex 39A at our Kennedy Space Center in Florida. The payload includes NICER, an instrument to measure neutron stars, and ROSA, a Roll-Out Solar Array that will test a new solar panel that rolls open in space like a party favor.

More

5. Sojourner

July 4, 2017: Twenty years ago, a wagon-sized rover named Sojourner blazed the trail for future Mars explorers - both robots and, one day, humans. Take a trip back in time to the vintage Mars Pathfinder websites:

More

6. Voyager

August 20, 2017: Forty years and still going strong, our twin Voyagers mark 40 years since they left Earth.

More

7. Total Solar Eclipse

August 21, 2017: All of North America will be treated to a rare celestial event: a total solar eclipse. The path of totality runs from Oregon to South Carolina.

More

8. From Science Fiction to Science Fact

Light a candle for the man who took rocketry from science fiction to science fact. On this day in 1882, Robert H. Goddard was born in Worcester, Massachusetts.

More

9. Looking at the Moon

October 28, 2017: Howl (or look) at the moon with the rest of the world. It's time for the annual International Observe the Moon Night.

More

10. Last Human on the Moon

December 13, 2017: Forty-five years ago, Apollo 17 astronaut Gene Cernan left the last human footprint on the moon.

More

Discover more lists of 10 things to know about our solar system HERE.

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Hail the Hexagon...

The full light of our sun allowed the Cassini spacecraft to capture this image of Saturn's hexagonal polar jet stream, but the sun does not provide much warmth. In addition to being low in the sky (just like summer at Earth's poles), the sun is nearly ten times as distant from Saturn as from Earth. This results in the sunlight being only about 1 percent as intense as at our planet. 

The view was obtained at a distance of approximately 560,000 miles (900,000 kilometers) from Saturn. Image scale is 33 miles (54 kilometers) per pixel.

More info: https://www.nasa.gov/image-feature/jpl/pia21327/hail-the-hexagon

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Take a dive between Saturn and its rings to see what our Cassini spacecraft saw during its first daring plunge on April 26! 

As Cassini made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. The video begins with a view of the vortex at Saturn's north pole, then heads past the outer boundary of the planet's hexagon-shaped jet stream and continues further southward. 

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It’s May the 4th: Are Star Wars Planets Real?

Look at what we’ve found so far.

Is your favorite Star Wars planet a desert world or an ice planet or a jungle moon?

It’s possible that your favorite planet exists right here in our galaxy. Astronomers have found over 3,700 planets around other stars, called “exoplanets.”

Some of these alien worlds could be very similar to arid Tatooine, watery Scarif and even frozen Hoth, according to our scientists.

Find out if your planet exists in a galaxy far, far away or all around you. And May the Fourth be with you!

Planets With Two Suns

From Luke Skywalker’s home world Tatooine, you can stand in the orange glow of a double sunset. The same could said for Kepler-16b, a cold gas giant roughly the size of Saturn, that orbits two stars. Kepler-16b was the Kepler telescope’s first discovery of a planet in a “circumbinary” orbit (that is, circling both stars, as opposed to just one, in a double star system). 

The best part is that Tatooine aka Kepler-16b was just the first. It has family. A LOT of family. Half the stars in our galaxy are pairs, rather than single stars like our sun. If every star has at least one planet, that’s billions of worlds with two suns. Billions! Maybe waiting for life to be found on them.

Desert Worlds

Mars is a cold desert planet in our solar system, and we have plenty of examples of scorching hot planets in our galaxy (like Kepler-10b), which orbits its star in less than a day)! Scientists think that if there are other habitable planets in the galaxy, they’re more likely to be desert planets than ocean worlds. That’s because ocean worlds freeze when they’re too far from their star, or boil off their water if they’re too close, potentially making them unlivable. Perhaps, it’s not so weird that both Luke Skywalker and Rey grew up on planets that look a lot alike.

Ice Planets

An icy super-Earth named OGLE-2005-BLG-390Lb reminded scientists so much of the frozen Rebel base they nicknamed it “Hoth,” after its frozen temperature of minus 364 degrees Fahrenheit. Another Hoth-like planet was discovered in April 2017; an Earth-mass icy world orbiting its star at the same distance as Earth orbits the sun. But its star is so faint, the surface of OGLE-2016-BLG-1195Lb is probably colder than Pluto.

Forest worlds

Both the forest moon of Endor and Takodana, the home of Han Solo’s favorite cantina in “Force Awakens,” are green like our home planet. But astrobiologists think that plant life on other worlds could be red, black, or even rainbow-colored!

In February 2017, the Spitzer Space Telescope discovered seven Earth-sized planets in the same system, orbiting the tiny red star TRAPPIST-1.

The light from a red star, also known as an M dwarf, is dim and mostly in the infrared spectrum (as opposed to the visible spectrum we see with our sun). And that could mean plants with wildly different colors than what we’re used to seeing on Earth. Or, it could mean animals that see in the near-infrared.

What About Moons?

In Star Wars, Endor, the planet with the cute Ewoks, is actually a habitable moon of a gas giant. Now, we’re looking for life on the moons of our own gas giants. Saturn’s moon Enceladus or Jupiter’s moon Europa are ocean worlds that may well support life. Our Cassini spacecraft explored the Saturn system and its moons, before the mission ended in 2017. Watch the video and learn more about the missions’s findings.

And Beyond

The next few years will see the launch of a new generation of spacecraft to search for planets around other stars. Our TESS spacecraft launched in April 2018, and will discover new exoplanets by the end of the year. The James Webb Space Telescope is slated to launch in 2020. That’s one step closer to finding life.

You might want to take our ‘Star Wars: Fact or Fiction?’ quiz. Try it! Based on your score you may obtain the title of Padawan, Jedi Knight, or even Jedi Master! 

You don’t need to visit a galaxy far, far away to find wondrous worlds. Just visit this one ... there’s plenty to see.

Discover more about exoplanets here: https://exoplanets.nasa.gov/

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What’s Up for May?

This month, Jupiter is well placed for evening viewing, Saturn rises before midnight and the moon dances with Venus, Mercury and Mars.  

Jupiter climbs higher in the southeast sky earlier in the evening this month, instead of having to wait until midnight for the planet to make an appearance. You can even see with just a pair of binoculars--even the four Galilean moon! 

You can even see with just a pair of binoculars--even Io, Europa, Ganymede and Callisto--the four Galilean moons--as they change position each night! 

Our moon appears near Jupiter in the nighttime sky from May 5-8.

The moon joins Venus and Mercury in the eastern sky just before sunrise on May 22 and May 23.

Later in the month, our moon pairs up with Mars in the west-northwest sky on May 26.

Saturn will be visible before midnight in early May, rising about 11:30 p.m. and by 9:30 p.m. later in the month. The best time to see Saturn Saturn is when it’s higher in the sky after midnight near the end of the month.

Using a telescope, you may be able to see Saturn’s cloud bands, or even a glimpse of Saturn’s north polar region--views that were beautifully captured by our Cassini spacecraft.

Watch the full video:

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This unprocessed image shows features in Saturn's atmosphere from closer than ever before. The view was captured by our Cassini spacecraft during its first Grand Finale dive between the planet and its rings on April 26, 2017.

As Cassini dove through the gap, it came within about 1,900 miles (3,000 kilometers) of Saturn's cloud tops (where the air pressure is 1 bar -- comparable to the atmospheric pressure of Earth at sea level) and within about 200 miles (300 kilometers) of the innermost visible edge of the rings.

See all the unprocessed images from Cassini: https://saturn.jpl.nasa.gov/galleries/raw-images/ 

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The Start of Cassini’s Grand Finale

Cue drumroll…

For the first time ever, our Cassini spacecraft dove through the narrow gap between Saturn and its rings on April 26. At 5 a.m. EDT, Cassini crossed the ring plane with its science instruments turned on and collecting data. 

During this dive, the spacecraft was not in contact with Earth. The first opportunity to regain contact with the spacecraft is expected around 3 a.m. EDT on April 27.

This area between Saturn and its rings has never been explored by a spacecraft before. What we learn from these daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve.

So, you might be asking…how did this spacecraft maneuver its orbit between Saturn and its rings? Well…let us explain!

On April 22, Cassini made its 127th and final close approach to Saturn’s moon Titan. The flyby put the spacecraft on course for its dramatic last act, known as the Grand Finale. 

As the spacecraft passed over Titan, the moon’s gravity bent its path, reshaping the robotic probe’s orbit slightly so that instead of passing just outside Saturn’s main rings, Cassini would begin a series of 22 dives between the rings and the planet.

With this assist, Cassini received a large increase in velocity of approximately 1,925 mph with respect to Saturn.

This final chapter of exploration and discovery is in many ways like a brand-new mission. Twenty-two times, the Cassini spacecraft will dive through the unexplored space between Saturn and its rings. What we learn from these ultra-close passes over the planet could be some of the most exciting revelations ever returned by the long-lived spacecraft.

Throughout these daring maneuvers, updates will be posted on social media at:

@CassiniSaturn on Twitter @NASAJPL on Twitter

Updates will also be available online at: https://saturn.jpl.nasa.gov/mission/grand-finale/milestones/ 

Follow along with us during this mission’s Grand Finale!

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Solar System: Things to Know This Week

Making every night science movie night with these amazing videos.

1. Pure Beauty 

Our star sprouting coronal loops courtesy of the NASA sun team. See the full video: https://go.nasa.gov/2p47Lt2

2. Where’s the last place you'd expect to find enough ice to bury a city? 

Answer: Mercury, the closest planet to the sun. Watch the video: https://svs.gsfc.nasa.gov/11184

3. The Mars Fleet 

Only Earth has more satellites studying it. Full video: https://svs.gsfc.nasa.gov/4414

4. A Star-Studded Cast

Check out NASA's satellite fleet of Earth observers. See the video: https://svs.gsfc.nasa.gov/12586

5. Jupiter in Ultra HD 

Thanks, Hubble Space Telescope! See the video: https://svs.gsfc.nasa.gov/12021

6. A Tear Jerker 

Our Cassini spacecraft starts her 4.5-month Grand Finale this week. Full video: https://saturn.jpl.nasa.gov/resources/7628

7. Faster Than the Speed of Sound

Winds on Neptune travel faster than the speed of sound. Full video: https://svs.gsfc.nasa.gov/11349

8. A Musical Number

This one features the planet Uranus doing pop and lock. Full video: https://youtu.be/CWuWoiHmXUs

9. Up Close and Personal 

Thanks to our New Horizons mission, we’ve been able to get up close and with Pluto. Full video: https://svs.gsfc.nasa.gov/12080

10: The Treasure Trove

TRAPPIST-1 is a treasure trove of seven Earth-sized planets orbiting a distant star. Full video: https://www.jpl.nasa.gov/video/details.php?id=1459

Discover more lists of 10 things to know about our solar system HERE.

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For NASA, Earth Day is Every Day!

With a fleet of spacecraft orbiting our home planet collecting data on everything from the air we breathe to natural disasters that impact our lives, Earth is always in focus. Join us as we celebrate our home with beautiful views from our unique vantage point of space.

On December 17, 1972, the crew of Apollo 17 snapped this iconic image of planet Earth. Dubbed the Blue Marble, this image was taken as Apollo 17 rocketed toward the moon. 

On the way to the moon or from the surface of Mars, our spacecraft have photographed the beauty of Earth from many vantage points. In this image, the most powerful telescope orbiting Mars captured this view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon. The image combines two separate exposures taken on November 20, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on our Mars Reconnaissance Orbiter. 

In this image taken on July 19, 2013, the wide-angle camera on our Cassini spacecraft captured Saturn's rings and our planet Earth and its moon in the same frame.

Our Suomi-NPP satellite also observed the Earth at night. Earth’s "night lights" often have a gee-whiz curiosity for the public , but have also served as a tool for fundamental research for nearly 25 years. They have provided a broad, beautiful picture, showing how humans have shaped the planet and lit up the darkness. 

You can be mesmerized by the constant swirls in these visualizations of ocean currents. The swirling flows of tens of thousands of ocean currents were captured using the largest computations of their kind ever undertaken, using high-end computing resources at our Ames Research Center. 

We’ve all seen iconic photographs of Earth shot by astronauts. But even satellites and robotic spacecraft often get in on the act. The above image, called “Pale Blue Dot,” was taken Voyager 1 in February 1990 from a distance of 4 billion miles.

Our satellites do more than take pretty pictures of Earth. They do everything from measure rainfall to observe weather patterns. The ten satellites in the Global Precipitation Measurement Constellation have provided unprecedented information about rain and snow fall across the entire Earth. This visualization shows the constellation in action, taking precipitation measurements underneath the satellite orbits. 

In an homage to Apollo 17′s “Blue Marble” image, Suomi-NPP, a joint NASA-NOAA Earth-observing satellite, made this composite image, by making a number of swaths of Earth's surface on January 4, 2012. 

What’s your favorite aspect of planet Earth? These kids have their own ideas. You can even “adopt” parts of the planet. Which one of the 64,000 locations will you get? 

Our home planet is constantly changing, which is why our fleet of Earth-observing satellites continuously monitor the globe, recording every moment of what they see. Luckily for us, many of the views are not only deeply informative but also awe-inspiring. 

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Solar System: Things to Know This Week

Reaching out into space yields benefits on Earth. Many of these have practical applications — but there's something more than that. Call it inspiration, perhaps, what photographer Ansel Adams referred to as nature's "endless prospect of magic and wonder." 

Our ongoing exploration of the solar system has yielded more than a few magical images. Why not keep some of them close by to inspire your own explorations? This week, we offer 10 planetary photos suitable for wallpapers on your desktop or phone. Find many more in our galleries. These images were the result of audacious expeditions into deep space; as author Edward Abbey said, "May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view."

1. Martian Selfie

This self-portrait of NASA's Curiosity Mars rover shows the robotic geologist in the "Murray Buttes" area on lower Mount Sharp. Key features on the skyline of this panorama are the dark mesa called "M12" to the left of the rover's mast and pale, upper Mount Sharp to the right of the mast. The top of M12 stands about 23 feet (7 meters) above the base of the sloping piles of rocks just behind Curiosity. The scene combines approximately 60 images taken by the Mars Hand Lens Imager, or MAHLI, camera at the end of the rover's robotic arm. Most of the component images were taken on September 17, 2016.

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2. The Colors of Pluto

NASA's New Horizons spacecraft captured this high-resolution, enhanced color view of Pluto on July 14, 2015. The image combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). Pluto's surface sports a remarkable range of subtle colors, enhanced in this view to a rainbow of pale blues, yellows, oranges, and deep reds. Many landforms have their own distinct colors, telling a complex geological and climatological story that scientists have only just begun to decode.

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3. The Day the Earth Smiled

On July 19, 2013, in an event celebrated the world over, our Cassini spacecraft slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings — and, in the background, our home planet, Earth. This mosaic is special as it marks the third time our home planet was imaged from the outer solar system; the second time it was imaged by Cassini from Saturn's orbit, the first time ever that inhabitants of Earth were made aware in advance that their photo would be taken from such a great distance.

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4. Looking Back

Before leaving the Pluto system forever, New Horizons turned back to see Pluto backlit by the sun. The small world's haze layer shows its blue color in this picture. The high-altitude haze is thought to be similar in nature to that seen at Saturn's moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles called tholins. This image was generated by combining information from blue, red and near-infrared images to closely replicate the color a human eye would perceive.

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5. Catching Its Own Tail

A huge storm churning through the atmosphere in Saturn's northern hemisphere overtakes itself as it encircles the planet in this true-color view from Cassini. This picture, captured on February 25, 2011, was taken about 12 weeks after the storm began, and the clouds by this time had formed a tail that wrapped around the planet. The storm is a prodigious source of radio noise, which comes from lightning deep within the planet's atmosphere.

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6. The Great Red Spot

Another massive storm, this time on Jupiter, as seen in this dramatic close-up by Voyager 1 in 1979. The Great Red Spot is much larger than the entire Earth.

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7. More Stormy Weather

Jupiter is still just as stormy today, as seen in this recent view from NASA's Juno spacecraft, when it soared directly over Jupiter's south pole on February 2, 2017, from an altitude of about 62,800 miles (101,000 kilometers) above the cloud tops. From this unique vantage point we see the terminator (where day meets night) cutting across the Jovian south polar region's restless, marbled atmosphere with the south pole itself approximately in the center of that border. This image was processed by citizen scientist John Landino. This enhanced color version highlights the bright high clouds and numerous meandering oval storms.

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8. X-Ray Vision

X-rays stream off the sun in this image showing observations from by our Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by our Solar Dynamics Observatory (SDO). The NuSTAR data, seen in green and blue, reveal solar high-energy emission. The high-energy X-rays come from gas heated to above 3 million degrees. The red channel represents ultraviolet light captured by SDO, and shows the presence of lower-temperature material in the solar atmosphere at 1 million degrees.

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9. One Space Robot Photographs Another

This image from NASA's Mars Reconnaissance Orbiter shows Victoria crater, near the equator of Mars. The crater is approximately half a mile (800 meters) in diameter. It has a distinctive scalloped shape to its rim, caused by erosion and downhill movement of crater wall material. Since January 2004, the Mars Exploration Rover Opportunity has been operating in the region where Victoria crater is found. Five days before this image was taken in October 2006, Opportunity arrived at the rim of the crater after a drive of more than over 5 miles (9 kilometers). The rover can be seen in this image, as a dot at roughly the "ten o'clock" position along the rim of the crater. (You can zoom in on the full-resolution version here.)

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10. Night Lights

Last, but far from least, is this remarkable new view of our home planet. Last week, we released new global maps of Earth at night, providing the clearest yet composite view of the patterns of human settlement across our planet. This composite image, one of three new full-hemisphere views, provides a view of the Americas at night from the NASA-NOAA Suomi-NPP satellite. The clouds and sun glint — added here for aesthetic effect — are derived from MODIS instrument land surface and cloud cover products.

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Americas at night

Discover more lists of 10 things to know about our solar system HERE.

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Hearing a lot about ocean worlds today? Let’s dive in and see what this news is all about...

We once thought oceans made our planet unique, but we’re now coming to realize that ‘ocean worlds’ are all around us.

Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other ‘ocean worlds’ in our solar system and beyond. The findings are presented in papers published Thursday by researchers with our Cassini mission to Saturn and Hubble Space Telescope. 

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Ocean Worlds Beyond Earth

We’re incredibly lucky to live on a planet drenched in water, nestled in a perfect distance from our sun and wrapped with magnetic fields keeping our atmosphere intact against harsh radiation and space weather.

We know from recent research that life can persist in the cruelest of environments here on Earth, which gives us hope to finding life thriving on other worlds. While we have yet to find life outside of Earth, we are optimistic about the possibilities, especially on other ocean worlds right here in our solar system.  

So…What’s the News?!

Two of our veteran missions are providing tantalizing new details about icy, ocean-bearing moons of Jupiter and Saturn, further enhancing the scientific interest of these and other “ocean worlds” in our solar system and beyond!

Cassini scientists announce that a form of energy for life appears to exist in Saturn’s moon Enceladus, and Hubble researchers report additional evidence of plumes erupting from Jupiter’s moon Europa.

The Two Missions: Cassini and Hubble

Cassini

Our Cassini spacecraft has found that hydrothermal vents in the ocean of Saturn’s icy moon Enceladus are producing hydrogen gas, which could potentially provide a chemical energy source for life.

Cassini discovered that this little moon of Saturn was active in 2005. The discovery that Enceladus has jets of gas and icy particles coming out of its south polar region surprised the world. Later we determined that plumes of material are coming from a global ocean under the icy crust, through large cracks known as “tiger stripes.” 

We have more evidence now – this time sampled straight from the plume itself – of hydrothermal activity, and we now know the water is chemically interacting with the rock beneath the ocean and producing the kind of chemistry that could be used by microbes IF they happened to be there.

This is the culmination of 12 years of investigations by Cassini and a capstone finding for the mission. We now know Enceladus has nearly all the ingredients needed for life as we know it.

The Cassini spacecraft made its deepest dive through the plume on Oct. 28, 2015. From previous flybys, Cassini determined that nearly 98% of the gas in the plume is water and the rest is a mixture of other molecules, including carbon dioxide, methane and ammonia. 

Cassini’s other instruments provided evidence of hydrothermal activity in the ocean. What we really wanted to know was…Is there hydrogen being produced that microbes could use to make energy? And that’s exactly what we found!

To be clear…we haven’t discovered microbes at Enceladus, but vents of this type at Earth host these kinds of life. We’re cautiously excited at the prospect that there might be something like this at Enceladus too!

Hubble

The Hubble Space Telescope has also been studying another ocean world in our solar system: Europa!

Europa is one of the four major moons of Jupiter, about the size of our own moon but very different in appearance. It’s a cold, icy world with a relatively smooth, bright surface crisscrossed with dark cracks and patches of reddish material.

What makes Europa interesting is that it’s believed to have a global ocean, underneath a thick crust of ice. In fact, it’s got about twice as much ocean as planet Earth!

In 2014, we detected evidence of intermittent water plumes on the surface of Europa, which is interesting because they may provide us with easier access to subsurface liquid water without having to drill through miles of ice.

And now, in 2016, we’ve found one particular plume candidate that appears to be at the same location that it was seen in 2014. 

This is exciting because if we can establish that a particular feature does repeat, then it is much more likely to be real and we can attempt to study and understand the processes that cause it to turn on or off. 

This plume also happens to coincide with an area where Europa is unusually warm as compared to the surrounding terrain. The plume candidates are about 30 to 60 miles (50 to 100 kilometers) in height and are well-positioned for observation, being in a relatively equatorial and well-determined location.

What Does All This Mean and What’s Next?

Hubble and Cassini are inherently different missions, but their complementary scientific discoveries, along with the synergy between our current and planned missions, will help us in finding out whether we are alone in the universe. 

Hubble will continue to observe Europa. If you’re wondering how we might be able to get more information on the Europa plume, the upcoming Europa Clipper mission will be carrying a suite of 9 instruments to investigate whether the mysterious icy moon could harbor conditions favorable for life. Europa Clipper is slated to launch in the 2020s.

This future mission will be able to study the surface of Europa in great detail and assess the habitability of this moon. Whether there’s life there or not is a question for this future mission to discover!

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Solar System: Things to Know This Week

Like sailors of old, the Cassini mission team fondly thinks of the spacecraft as "she."  On April 22, she begins her Grand Finale, a spectacular end game—22 daring dives between the planet's atmosphere and innermost rings. Here are 10 things to know about her Grand Finale.

1. She's Broadcasting Live This Week

On Tuesday, April 4 at 3 p.m. EDT  (noon PDT), At Jet Propulsion Laboratory, the Cassini team host a news briefing to discuss the mission's Grand Finale.

Tune in Tuesday: youtube.com/nasajpl/live

2. She's Powered in Part By ... Titan

Cassini left Earth with less than 1/30th of the propellant needed to power all her adventures at Saturn. The navigation team used the gravity of Saturn's giant moon Titan to change course and extend the spacecraft's exploration of Saturn. Titan also provides the gravity assist to push Cassini into its final orbits.

More on Cassini's navigation: saturn.jpl.nasa.gov/mission/spacecraft/navigation/

3. She's a Robot

Cassini is an orbiter that was named for 18th century astronomer Giovanni Domenico Cassini. She was designed to be captured by Saturn's gravity and then explore it in detail with a suite of 12 powerful science instruments.

More on the Spacecraft: saturn.jpl.nasa.gov/mission/spacecraft/cassini-orbiter/

4. She Brought a Friend to Saturn

Cassini carried the European Space Agency's Huygens Probe, which in 2005 descended through Titan's thick, perpetual clouds and made the most distant landing to date in our solar system.

More on Huygens: saturn.jpl.nasa.gov/mission/spacecraft/huygens-probe/

5. She's a Great Photographer

Your mobile phone likely captures dozens of megapixels in images. Cassini, using 1990s technology closer to one megapixel cameras, has returned some of the most stunning images in the history of solar system exploration.

Cassini Hall of Fame Images: go.nasa.gov/2oec6H2 More on Cassini's Cameras: saturn.jpl.nasa.gov/imaging-science-subsystem/

6. She's an Inspiration

Those great images have inspired artist's and amateur image processors to create truly fantastic imagery inspired by the beauty of Saturn. Feeling inspired? There's still time to share your Cassini-inspired art with us.

Cassini Inspires Campaign: saturn.jpl.nasa.gov/mission/cassiniinspires/

7. She's Got a Long History

Two decades is a long time to live in the harsh environment of outer space (respect to the fast-approaching 40-year-old twin Voyager spacecraft). Launched in 1997, Cassini logged a lot of milestones over the years.

Explore the Cassini Timeline: saturn.jpl.nasa.gov/the-journey/timeline/

8. She Keeps a Diary

And, you can read it. Week after week going back to 1997, Cassini's adventures, discoveries and status have been chronicled in the mission's weekly significant events report.

Read It: https://saturn.jpl.nasa.gov/news/?topic=121

9. She's Got a Fancy New App

Cassini was the prototype for NASA's Eyes on the Solar System 3-D visualization software, so it's fitting the latest Cassini module in the free, downloadable software is the most detailed, elaborate visualization of any mission to date.

Fly the Mission - Start to Finish: http://eyes.nasa.gov/cassini

10. She's Going Out in a Blaze of Glory

In addition to all the new information from 22 orbits in unexplored space, Cassini's engineers reprogrammed the spacecraft to send back details about Saturn's atmosphere to the very last second before the giant planet swallows her up on Sept. 15, 2017.

More on the Grand Finale: saturn.jpl.nasa.gov/grandfinale

Discover more lists of 10 things to know about our solar system HERE.

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Pi Guides the Way

It may be irrational but pi plays an important role in the everyday work of scientists at NASA. 

What Is Pi ?

Pi is the ratio of a circle’s circumference to its diameter. It is also an irrational number, meaning its decimal representation never ends and it never repeats. Pi has been calculated to more than one trillion digits, 

Why March 14?

March 14 marks the yearly celebration of the mathematical constant pi. More than just a number for mathematicians, pi has all sorts of applications in the real world, including on our missions. 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).

While 3.14 is often a precise enough approximation, hence the celebration occurring on March 14, or 3/14 (when written in standard U.S.  month/day format), the first known celebration occurred in 1988, and in 2009, the U.S. House of Representatives passed a resolution designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi.

5 Ways We Use Pi at NASA

Below are some ways scientists and engineers used pi.

Keeping Spacecraft Chugging Along

Propulsion engineers use pi to determine the volume and surface area of propellant tanks. It’s how they size tanks and determine liquid propellant volume to keep spacecraft going and making new discoveries. 

Getting New Perspectives on Saturn

A technique called pi transfer uses the gravity of Titan’s moon, Titan, to alter the orbit of the Cassini spacecraft so it can obtain different perspectives of the ringed planet.

Learning the Composition of Asteroids

Using pi and the asteroid’s mass, scientists can calculate the density of an asteroid and learn what it’s made of--ice, iron, rock, etc.

Measuring Craters

knowing the circumference, diameter and surface area of a crater can tell scientists a lot about the asteroid or meteor that may have carved it out.

Determining the Size of Exoplanets

Exoplanets are planets that orbit suns other than our own and scientists use pi to search for them. The first step is determining how much the light curve of a planet’s sun dims when a suspected planets passes in front of it.

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Solar System: Things to Know This Week

Has Cassini inspired you? Learn more about dwarf planet Ceres, get the latest images from the Keck Observatory and more!

1. Has Cassini Inspired You?

During nearly two decades in space, Cassini has been a source of inspiration to many. Has Cassini inspired you? Upload your artwork, photos, poems or songs to the social media platform of your choice, such as Instagram, YouTube, Facebook, Twitter or others. Tag it #CassiniInspires. Or, send it directly to: cassinimission@jpl.nasa.gov. We'll highlight some of the creations on this page. See examples and details at: saturn.jpl.nasa.gov/mission/cassiniinspires/

2. Dawn’s Shines a Light on Ceres

Our Dawn mission has found evidence for organic material on Ceres, a dwarf planet and the largest body in the main asteroid belt between Mars and Jupiter. Learn more: solarsystem.nasa.gov/news/2017/02/17/dawn-discovers-evidence-for-organic-material-on-ceres

3. Into the Vortex

A new device called the vortex coronagraph was recently installed inside NIRC2 (Near Infrared Camera 2) at the W.M. Keck Observatory in Hawaii and has delivered its first images, showing a ring of planet-forming dust around a star, and separately, a cool, star-like body, called a brown dwarf, lying near its companion star.

4. Enceladus: Cassini Cracks the Code of the Icy Moon

A puzzling sensor reading transformed our Cassini Saturn mission and created a new target in the search for habitable worlds beyond Earth, when on Feb. 17, 2005, Cassini made the first-ever close pass over Saturn’s moon. Since our two Voyager spacecraft made their distant flybys of Enceladus about 20 years prior, scientists had anticipated the little moon would be an interesting place to visit. Enceladus is bright white -- the most reflective object in the solar system, in fact -- and it orbits in the middle of a faint ring of dust-sized ice particles known as Saturn’s E ring. Scientists speculated ice dust was being kicked off its surface somehow. But they presumed it would be, essentially, a dead, airless ball of ice.

What Cassini saw didn't look like a frozen, airless body. Instead, it looked something like a comet that was actively emitting gas. The magnetometer detected that Saturn’s magnetic field, which envelops Enceladus, was perturbed above the moon's south pole in a way that didn't make sense for an inactive world. Could it be that the moon was actively replenishing gases it was breathing into space? Watch the video.

5. Descent Into a Frozen Underworld

Our planet's southernmost active volcano reaches 12,448 feet (3,794 meters) above Ross Island in Antarctica. It's a good stand-in for a frozen alien world, the kind we want to send robots to someday. Learn more: solarsystem.nasa.gov/news/2017/02/13/descent-into-a-frozen-underworld

Discover the full list of 10 things to know about our solar system this week HERE.

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Solar System: Things to Know This Week

Follow our Juno craft during a close flyby of Jupiter, learn about Cassini’s final mission during a Facebook live event (in case you missed it) and more!

1. Jupiter, Up Close

Our Juno mission completed a close flyby of Jupiter on Thursday, February 2, its latest science orbit of the mission. All of Juno's science instruments and the spacecraft's JunoCam were operating during the flyby to collect data that is now being returned to Earth. 

Want to know more? Using NASA's Eyes on the Solar System and simulated data from the Juno flight team you can ride onboard the Juno spacecraft in real-time at any moment during the entire mission.

2. In Case You Missed It--Cassini Facebook Live

Cassini Project Scientist Linda Spilker and mission planner Molly Bittner take questions about the mission's "Ring-Grazing" orbits during Facebook Live. Watch it now: www.facebook.com/NASA/videos/10154861046561772/

3. Cassini Scientist for a Day Essay Contest 

The deadline is Friday, February 24 for U.S. student in grades 5 to 12. For international students, visit the page for more info! 

More: solarsystem.nasa.gov/educ/Scientist-For-a-Day/2016-17/videos/intro

4. Cassini Spies Dione

Dione's lit hemisphere faces away from Cassini's camera, yet the moon's darkened surface are dimly illuminated in this image, due to the phenomenon of Saturnshine. Although direct sunlight provides the best illumination for imaging, light reflected off of Saturn can do the job as well. In this image, Dione (698 miles or 1,123 kilometers across) is above Saturn's day side, and the moon's night side is faintly illuminated by sunlight reflected off the planet's disk.

Discover the full list of 10 things to know about our solar system this week HERE.

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Solar System: Things to Know This Week

Learn more about the speed and final mission for Cassini, citizen science on Jupiter and more!

1. Cassini's Two Speeds

Our Cassini spacecraft is blazingly fast. How fast? Well, that's all relative. Learn about the need for speed in space navigation.

2. Daphnis, the Wavemaker

The wavemaker moon, Daphnis, is featured in this view, taken as our Cassini spacecraft made one of its ring-grazing passes over the outer edges of Saturn's rings on earlier this month. This is the closest view of the small moon obtained to date.

3. Cassini's Grand Finale

The European Space Agency’s tracking antennas at New Norcia, Western Australia, and Malargüe, Argentina, are helping with crucial observations during Cassini's last months in orbit, dubbed the 'Grand Finale.'

4. Citizen Science—in Space

This image of a crescent Jupiter and the iconic Great Red Spot was created by a citizen scientist Roman Tkachenko using data from Juno spacecraft's onboard camera. The images also bear witness a series of storms shaped like white ovals, known informally as the "string of pearls." 

5. 360 video: Rover Ride-Along in the Mars Yard

Get a robot's-eye-view of the "Mars Yard," a terrain simulation area at the Jet Propulsion Laboratory where rover hardware and software are tested before being sent to the Red Planet. Ride alongside, atop and below the Scarecrow test mobility double for the Curiosity and Mars 2020 rovers.

Watch the video: www.youtube.com/watch Learn more about Scarecrow: http://mars.jpl.nasa.gov/news/2014/scarecrow-rover-goes-off-roading-in-dumont-dunes

Discover the full list of 10 things to know about our solar system this week HERE.

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