Jupiter and Its Not-So-Great Red Spot

Jupiter's Great Red Spot is a churning anticyclonic storm. It shows up in images of the giant planet as a conspicuous deep red eye embedded in swirling layers of pale yellow, orange and white. Winds inside this Jovian storm rage at immense speeds, reaching several hundreds of kilometers per hour.

Historic observations as far back as the late 1800s gauged this turbulent spot to span about 41 000 kilometers at its widest point – wide enough to fit three Earths comfortably side by side. In 1979 and 1980 the NASA Voyager fly-bys measured the spot at a shrunken 23,335 kilometers across. Now, Hubble has spied this feature to be smaller than ever before.

This full-disc image of Jupiter was taken on 21 April 2014 with Hubble's Wide Field Camera 3 (WFC3).

Image credit: NASA, ESA, and A. Simon (Goddard Space Flight Center)

Note: For more information, see The Shrinking of Jupiter's Great Red Spot, Jupiter's Great Red Spot is Smaller Than Ever Measured, and Jupiter's Great Red Spot is Shrinking.

Ganymede's Possible Internal Structure

This artist's concept of Jupiter's moon Ganymede, the largest moon in the solar system, illustrates the "club sandwich" model of its interior oceans. Scientists suspect Ganymede has a massive ocean under an icy crust. In fact, Ganymede's oceans may have 25 times the volume of those on Earth. Previous models of the moon showed the moon's ocean sandwiched between a top and bottom later of ice. A new model, based on experiments in the laboratory that simulate salty seas, shows that the ocean and ice may be stacked up in multiple layers, more like a club sandwich.

Ice comes in different forms depending on pressures. "Ice I," the least dense form of ice, is what floats in your chilled beverages. As pressures increase, ice molecules become more tightly packed and thus more dense. Because Ganymede's oceans are up to 500 miles (800 kilometers) deep, they would experience more pressure than Earth's oceans. The deepest and most dense form of ice thought to exist on Ganymede is called "Ice VI."

When researchers added in salt into their models of the ocean, they found the situation changed from what was previously thought. With enough salt, liquid in Ganymede can become dense enough to sink to the very bottom of the seafloor, below Ice VI. Their models also suggest a complex stacking of ocean and ice, as illustrated in the picture.

What's more, the model shows that a strange phenomenon might occur in the uppermost liquid layer, where ice floats upward. In this scenario, cold plumes cause Ice III to form. As the ice forms, salt precipitates out. The salt then sinks down while the ice "snows" upward. Eventually, this ice would melt, resulting in a slushy layer in Ganymede's club sandwich structure.

Scientists say this structure may not be stable. It's possible the moon goes through a club sandwich phase, while at other times goes back to being more like a regular sandwich, with one ocean sitting below the familiar Ice I found on Earth and on top of different high-pressure ices.

The fact that salty water may persist at the bottom of the rocky seafloor, rather than ice, is favorable for the development of life. Researchers think life emerges through a series of chemical interactions at water-mineral interfaces, so a wet seafloor on Ganymede might be a key ingredient for life there.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Ganymede May Harbor 'Club Sandwich' of Oceans and Ice.

Source Region for Possible Europa Plumes

This reprojection of the official USGS Europa basemap is centered at the estimated source region for potential plumes that might have been detected using the Hubble Space Telescope. The view is centered at -65 degrees latitude, 183 degrees longitude.

In addition to the plume source region, the image also shows the hemisphere of Europa that might be affected by plume deposits. This map is composed of images from NASA's Galileo and Voyager missions. The black region near the south pole results from gaps in imaging coverage.

Image credit: NASA/JPL-Caltech/SETI Institute

Ganymede Geological Map

Animation of a rotating globe of Jupiter's moon Ganymede, with a geologic map superimposed over a global color mosaic. The 37-second animation begins as a global color mosaic image of the moon then quickly fades in the geologic map.

The views incorporate the best available imagery from NASA's Voyager 1 and 2 spacecraft and NASA's Galileo spacecraft.

To present the best information in a single view of Jupiter's moon Ganymede, a global image mosaic was assembled, incorporating the best available imagery from NASA's Voyager 1 and 2 spacecraft and NASA's Galileo spacecraft. This image shows Ganymede centered at 200 west longitude. This mosaic (right) served as the base map for the geologic map of Ganymede (left).

Video credit (top): USGS Astrogeology Science Center/Wheaton/ASU/NASA/JPL-Caltech; image credit (bottom): USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech

Note: For more information, see Largest Solar System Moon Detailed in Geologic Map.

Cilix Crater Digital Elevation Model

This view of Cilix impact crater on Europa was created in 2013 using 3-D stereo images taken by NASA's Galileo spacecraft, combined with advanced image processing techniques. The crater has a diameter of about 11 miles (18 kilometers).

This image, which combines a 3-D Digital Elevation Model, or DEM, with original imagery, shows that the crater rim rises steeply for about 980 feet (300 meters) above a flat crater floor that is interrupted by a central peak which has a height of about 660 feet (200 meters). Such central peaks are common on other bodies in the solar system. Young, well-preserved craters like Cilix are rare on Europa's surface, where ongoing geologic activity is thought to disrupt most surface features over timescales of tens of millions of years.

Image credit: NASA/JPL-Caltech

Water Vapor from Europa

This graphic shows the location of water vapor detected over Europa's south pole in observations taken by NASA's Hubble Space Telescope in December 2012. This is the first strong evidence of water plumes erupting off Europa's surface.

Hubble didn't photograph plumes, but spectroscopically detected auroral emissions from oxygen and hydrogen. The aurora is powered by Jupiter's magnetic field. This is only the second moon in the solar system found ejecting water vapor from the frigid surface. The image of Europa is derived from a global surface map generated from combined observations taken by NASA's Voyager and Galileo space probes.

Image credit: NASA/ESA/L. Roth/SWRI/University of Cologne


Note: For more information, see Hubble Discovers Water Vapor Venting from Jupiter's Moon Europa, PIA17659: Artist's Concept of Europa Water Vapor Plume, and Hubble Sees Evidence of Water Vapor at Jupiter Moon.

Clay Minerals on Europa

This image, using data from NASA's Galileo mission, shows the first detection of clay-like minerals on the surface of Jupiter's moon Europa. The clay-like minerals appear in blue in the false-color patch of data from Galileo's Near-Infrared Mapping Spectrometer. Surfaces richer in water ice appear in red. The background image is a mosaic of images from Galileo's Solid State Imaging system in the colors that human eyes would see.

Scientists think an asteroid or comet impact could have delivered the clay-type minerals to Europa because these minerals are commonly found in these primitive celestial bodies. These kinds of asteroids and comets also typically carry organic compounds.

A version of the image without the infrared area is on the right.

Image credit: NASA/JPL-Caltech

Note: For more information, see PIA17657: Hit Hard: Possible Collision at Europa (Artist's Concept) and Clay-Like Minerals Found on Icy Crust of Europa.

Juno's Flyby of the Earth and Moon

This movie sequence of images was captured by a star tracker camera on NASA's Jupiter-bound Juno spacecraft. It was taken over several days as Juno approached Earth for a close flyby that would send the spacecraft onward to the giant planet. Although grainy and over-exposed, the images provide a nonetheless remarkable and uncommon view from a human-made craft approaching our world from deep space.

The images that make up this movie sequence were acquired by one of the four cameras that comprise Juno's Advanced Stellar Compass, or ASC -- a key component of the Juno magnetometer experiment. The ASC cameras provide images of the stars that reveal precisely the spacecraft's orientation in space, which will be vital for determining the strength and direction of Jupiter's magnetic field once Juno arrives there in 2016.

As star trackers, the cameras were not designed for imaging the planets. This sequence exists because of their serendipitous placement on the spacecraft -- situated on Juno's magnetometer boom, at the end of one of the craft's large solar arrays. The cameras happened to be pointed in Juno's direction of motion during the flyby, allowing this movie sequence to be obtained.

The movie begins at 2:00 UTC on October 6, more than four days before Juno's closest approach, when the spacecraft was approximately 2.1 million miles (3.3 million kilometers) from Earth. Earth's moon is seen transiting in front of our planet, and then moves out of frame toward the right as Juno enters the space inside the orbit of our natural satellite. As Juno gets closer to Earth, hints of clouds and continents are visible before the planet's brightness overwhelms the cameras, which were not designed to image so bright an object. The sequence ends as Earth passes out of view, which corresponds to approximately 17:35 UTC October 9 when Juno was at an altitude of about 47,000 miles (76,000 kilometers) above Earth's surface.

The sequence is replayed in the second half of this movie at two times and eight times magnification.

As Juno is a spinning spacecraft, the images were aligned to remove their apparent rotation. The original ASC images are monochrome; faint coloration has been added by converting the measured grayscale values into false colors matching a true color image of Earth.

Music Courtesy: Vangelis (used with permission).

Video credit: NASA/JPL-Caltech/DTU

Note: For more information, see PIA17744: Juno Detects a Ham Radio "HI" from Earth and NASA's Juno Gives Starship-Like View of Earth Flyby.

Cracks and Ridges on Europa

This enhanced color image shows cracks and ridges on Europa's surface that reveal a detailed geologic history. Some ridges, such as the prominent one at top right, develop into long, arc-shaped "cycloids" that may be related to changing tidal forces as Europa orbits Jupiter. The wall of this ridge stands perhaps a third of a mile (0.5 kilometer) above the surrounding ridged plains, although the edges are likely not as steep as they appear in this view.

The view was captured by NASA's Galileo spacecraft on February 2, 1999, during its E19 orbit, when the spacecraft was about 2500 miles (4000 km) from the surface of Europa. Resolution in the scene is 295 feet (90 meters) per pixel. North is toward bottom left. Images taken through near-infrared, green and violet filters were combined to create the view.

Image credit: NASA/JPL-Caltech

Earth, by Juno

On October 9, NASA's Juno spacecraft flew past Earth, using our home planet's gravity to get the final boost it needed to reach Jupiter. The JunoCam instrument captured this monochrome view of Earth, and other instruments were tested to ensure they work as designed during a close planetary encounter.

The Juno spacecraft was launched from NASA's Kennedy Space Center in Florida on August 5, 2011. Juno's rocket, the Atlas 551, was only capable of giving Juno enough energy or speed to reach the asteroid belt, at which point the Sun's gravity pulled Juno back toward the inner solar system. The Earth flyby gravity assist put Juno on course for arrival at Jupiter on July 4, 2016.

Photo credit: NASA/JPL-Caltech/Malin Space Science Systems

Note: For more information, see PIA17516: Juno's Earth Flyby (Artist's Rendering).

Artist's Conception of Europa's Surface

This artist's concept shows a simulated view from the surface of Jupiter's moon Europa. Europa's potentially rough, icy surface, tinged with reddish areas that scientists hope to learn more about, can be seen in the foreground. The giant planet Jupiter looms over the horizon.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see PIA17042: A Possible Lander with Tools for Europa and If We Landed on Europa, What Would We Want to Know?

New Names for Three Sulci and One Regio on Ganymede

From the USGS Astrogeology Science Center:

The Working Group for Planetary System Nomenclature has approved new names for four features on Ganymede: Melotte Regio, Babylon Sulci, Borsippa Sulcus, and Mummu Sulci. For more information, see the Gazetteer of Planetary Nomenclature.

Distribution of Water in Jupiter's Stratosphere

This map shows the distribution of water in the stratosphere of Jupiter as measured with ESA's Herschel space observatory. White and cyan indicate highest concentration of water, and blue indicates lesser amounts. The map has been superimposed over an image of Jupiter taken at visible wavelengths with the NASA/ESA Hubble Space Telescope.

The distribution of water clearly shows an asymmetric distribution across the planet's disc: water is more abundant in the southern hemisphere. Based on this and other clues collected with Herschel, astronomers have established that at least 95 per cent of the water currently present in Jupiter's stratosphere has been supplied by comet Shoemaker-Levy 9, which famously impacted the planet at intermediate southern latitudes in 1994.

The map is based on spectrometric data collected with the PACS instrument on board Herschel around 66.4 microns, a wavelength that corresponds to one of water's many spectral signatures.

Image credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Note: For more information, see Herschel Links Water in Stratosphere to 1994 Comet Impact and Herschel Links Water Around Jupiter to Comet Impact.

Energy From Above Affecting Surface of Europa

This graphic of Jupiter's moon Europa maps a relationship between the amount of energy deposited onto the moon from charged-particle bombardment and the chemical contents of ice deposits on the surface in five areas of the moon (labeled A through E).

Energetic ions and electrons tied to Jupiter's powerful magnetic field smack into Europa as the field sweeps around Jupiter. The magnetic field travels around Jupiter even faster than Europa orbits the planet. Most of the energetic particles hitting Europa strike the moon's "trailing hemisphere," the half facing away from the direction Europa travels in its orbit. The "leading hemisphere," facing in the direction of travel, receives fewer of the charged particles.

Researchers assessed the amount of sulfate hydrates -- compared with relatively pristine water -- in the surface ice in five widely distributed areas of Europa. They used data from observations made by the near infrared spectrometer (NIMS) instrument on NASA's Galileo spacecraft, which orbited Jupiter from 1995 to 2003. They found that the concentration of frozen sulfuric acid on the surface varies greatly. It ranges from undetectable levels near the center of Europa's leading hemisphere, to more than half of the surface material near the center of the trailing hemisphere. The concentration is closely related to the amount of energy received from electrons and sulfur ions striking the surface, with a distribution controlled by interactions between Jupiter and Europa's magnetic fields.

This pattern could provide direction for the best places to study the surface of Europa for learning about material churned up from the moon's subsurface, which includes a deep saltwater ocean beneath an icy shell. The portions of the surface least affected by the bombardment of charged particles from above are most likely to preserve the original chemical compounds that erupted from the interior. Understanding the chemical ingredients of Europa's subsurface ocean could help scientists determine whether, as many suspect, the ocean could have supported life in the past or even now.

The images of Europa used for the base maps of this figure were taken by the solid state imager on Galileo. The areas labeled A through E are the areas covered by five sets of NIMS observations, and color-coded with darker, bluer portions having more sulfate hydrates and brighter, pinker portions having more water ice. The mapped patterns for energy input are derived from models for the flux of electrons and ions delivered by Jupiter's magnetic field. The color-code key at the right is labeled in units of mega electron volts per square centimeter per second.

Image Credit: NASA/JPL-Caltech/University of Arizona/JHUAPL/University of Colorado

Note: For more information, see Where are the Best Windows Into Europa's Interior?

Europa in Natural and Enhanced Colors

This color composite view combines violet, green, and infrared images of Jupiter's intriguing moon, Europa, for a view of the moon in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa's surface is composed mostly of water ice, with very few non-ice materials. In contrast, the brownish mottled regions on the right side of the image may be covered by hydrated salts and an unknown red component. The yellowish mottled terrain on the left side of the image is caused by some other unknown component. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.

North is to the top of the picture and the sun fully illuminates the surface. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth's moon. The finest details that can be discerned are 25 kilometers across. The images in this global view were taken in June 1997 at a range of 1.25 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft, during its ninth orbit of Jupiter.

Image credit: NASA/JPL/University of Arizona

Note: For more information, see Mapping the Chemistry Needed for Life at Europa.

Io Predicted Heat Flow Map

This map shows predicted heat flow at the surface of Jupiter's moon Io from two tidal-heating models. Red indicates areas where more heat is expected; blue where less heat is expected.

Figure A predicts surface heat concentration at the poles if tidal heating occurs primarily within Io's deep mantle.

Figure B shows surface heat concentrations at the equator if heating occurs primarily within Io's shallower asthenosphere.

Map credit: NASA/Christopher Hamilton

Io's Tvashtar Volcano

This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year [2007], this first-ever "movie" of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.

The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.

Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.

The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.

The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Note: For more information, see Scientists to Io: Volcanoes are in the Wrong Spot.

Vortices Bump into a Hot Spot in Jupiter's Atmosphere

In this series of images from NASA's Cassini spacecraft, a dark, rectangular hot spot (top) interacts with a line of vortices that approaches from on the upper-right side (second panel). The interaction distorts the shape of the hot spot (third panel), leaving it diminished (bottom). The black scale bar is about 6,200 miles (10,000 kilometers) wide, or about twice as wide as the United States.

From top to bottom, these images were taken on November 21, November 24, November 27 and December 3, 2000 by Cassini's imaging science subsystem.

Image credit: NASA/JPL-Caltech/SSI/GSFC

Note: For more information, see 'Hot Spots' Ride a Merry-Go-Round on Jupiter.

Dark Hot Spot in Jupiter's Atmosphere

The dark hot spot in this false-color image from NASA's Cassini spacecraft is a window deep into Jupiter's atmosphere. All around it are layers of higher clouds, with colors indicating which layer of the atmosphere the clouds are in. The bluish clouds to the right are in the upper troposphere, or perhaps higher still, in the stratosphere. The reddish gyre under the hot spot to the right and the large reddish plume at its lower left are in the lower troposphere. In addition, a high, gauzy haze covers part of the frame. An annotated version of this image highlights the hot spot in the middle with an arrow and boxes around the plume and the gyre.

This image was taken on December 13, 2000, by Cassini's imaging science subsystem.

Image credit: NASA/JPL-Caltech/SSI/GSFC

Note: For more information, see 'Hot Spots' Ride a Merry-Go-Round on Jupiter.

Europa Ocean and Geyser Hypothesis

Based on new evidence from Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up from the icy moon's global liquid ocean and reach the frozen surface where they are bombarded with sulfur from volcanoes on Jupiter's innermost large moon, Io. The new findings propose answers to questions that have been debated since the days of NASA's Voyager and Galileo missions. This illustration of Europa (foreground), Jupiter (right) and Io (middle) is an artist's concept.

Illustration credit: NASA/JPL-Caltech