The Solar System:


“Jupiter and Semele” by Gustave Moreau (1826-1898 CE; French), painted between 1889 and 1895.

The mortal woman Semele was treacherously advised by the goddess Juno, Jupiter’s wife, to ask him to appear to her in all his divine splendor. He obliged, but, in so doing, brought about her violent death by his divine thunder and lightning.

Credit: Gustave Moreau (between 1889 and 1895); Musee Gustave-Moreau, Paris [link]

Jupiter - king of the planets (at least in our solar system). More than 11 Earths fit across the diameter of Jupiter.

Credit: D. W. Hoard (2018), using public domain NASA images

Jupiter in 2016 from the Hubble Space Telescope (red hues emphasized).

Credit: NASA, ESA, Hubble, OPAL Program, STScI; Processing: Karol Masztalerz; Astronomy Picture of the Day on 2018 April 25 [link]

The Great Red Spot is an anticyclone (high pressure storm) wider than Earth that has persisted for hundreds of years (possibly the earliest report is from 1665). This image of the region around the Great Red Spot was obtained by Voyager 1 in 1979.

Credit: NASA/JPL [link]

Why is the Great Red Spot red? The exact answer is unknown, but probably we are seeing chemical compounds that are present in a deeper layer of Jupiter’s atmosphere pulled to the surface or exposed by the 400 mph surface winds in this enormous storm system. This highly detailed image of the Great Red Spot was obtained by the Juno spacecraft in 2017.

Credit: NASA/SwRI/MSSS/David Marriott [link]
Credit: NASA/JPL [link]

Bands, belts, and zones

Scientists produced new global maps of Jupiter in 2015 using the Wide Field Camera 3 on NASA's Hubble Space Telescope. One color map is shown here, projected as a flat image. The horizontal bands that encircle Jupiter show views of different layers in the upper atmosphere propelled in alternating opposite directions by "jet stream" wind systems. The dark bands of warmer, sinking gases are called belts, while the light bands of colder, rising gases are called zones.

Credit (image and some text): NASA/ESA/GSFC/UCBerkeley/JPL-Caltech/STScI [link]

The first color movie of Jupiter from NASA's Cassini spacecraft shows what it would look like to peel the entire globe of Jupiter, stretch it out on a wall into the form of a rectangular map, and watch its atmosphere evolve with time. This brief movie clip spans 24 Jupiter rotations between 31 October and 9 November 2000.

Various patterns of motion are apparent all across Jupiter at the cloudtop level seen here. The Great Red Spot shows its counterclockwise rotation. To the east (right) of the Red Spot, oval storms roll over and pass each other. Horizontal bands adjacent to each other move at different rates. The large grayish-blue "hot spots" at the northern edge of the white Equatorial Zone change over the course of time as they march eastward across the planet. Oval storms in the north rotate in the opposite direction to those in the south. Small, very bright features appear quickly and randomly in turbulent regions, candidates for lightning storms.

The smallest visible features at the equator are about 600 kilometers (about 370 miles) across. In a map of this nature, the most extreme northern and southern latitudes are unnaturally stretched out.

Credit (image and some text): NASA/JPL/University of Arizona [link]

The Great Red Spot is shrinking!

Jupiter's trademark Great Red Spot - a swirling storm feature larger than Earth - has shrunk to its smallest size ever measured. NASA Hubble Space Telescope observations in 2014 confirm the Great Red Spot now is approximately 10,250 miles (16,500 kilometers) across. In the comparison images, one Hubble photo was taken in 1995 by the Hubble's Wide Field and Planetary Camera 2 (WFPC2) when the long axis of the Great Red Spot was estimated to be 13,020 miles (20,950 kilometers) across. In a 2009 photo, after WFPC2 had been replaced by the Wide Field Camera 3 (WFC3), the storm was measured at 11,130 miles (17,910 kilometers) across. The dashed blue oval in each panel shows the size of the Great Red Spot in the 1995 image.

Historic observations as far back as the late 1800s (see below) gauged the Great Red Spot to be as big as 25,500 miles (41,000 kilometers) on its long axis. NASA's Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured the storm to be 14,500 miles (23,300 kilometers) across.

Credit (image and some text): NASA/JPL [link]

Comparison of the size of Jupiter's Great Red Spot in a ground-based photograph from 1879 and and a Hubble Space Telescope image from 2014. Both images are oriented with Jupiter's south pole at the top to match the inverted view obtained through the telescope used in 1879.

Credit: B. King, 2015 (June 15), - "UK amateur recreates the Great Red Spot's glory days" [link]; 1879 photo: from "A History of Astronomy in the 19th Century" by Agnes Clerk; 2014 photo: NASA/JPL

Take that Saturn! Jupiter also has rings!

This mosaic of Jupiter's ring system was acquired by NASA's Galileo spacecraft in 1998, when the Sun was behind the planet and the spacecraft was in Jupiter's shadow peering back toward the Sun. In such a configuration, very small dust-sized particles are accentuated so both the ring particles and the smallest particles in the upper atmosphere of Jupiter are highlighted.

Credit (image and some text): NASA/JPL/Cornell University [link]

Jupiter’s rings are composed of mostly dark rock dust from meteorite impacts on moons. Saturn’s rings are mostly highly reflective (bright) ice with only a small amount of rocky material.

The New Horizons spacecraft took the best images of Jupiter's charcoal-black rings while on its way to Pluto. The top image was taken on approach, showing three well-defined lanes of gravel- to boulder-sized material composing the bulk of the rings, as well as lesser amounts of material between the rings. New Horizons snapped the lower image after it had passed Jupiter on 28 February 2007 and looked back in a direction toward the Sun. The image is sharply focused, though it appears fuzzy due to the cloud of dust-sized particles enveloping the rings. Jupiter's narrow rings are confined in their orbits by small "shepherding" moons.

Credit (image and some text): NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute [link]

Comet Shoemaker-Levy 9

  • Comet SL-9 was discovered in July 1993.

  • It had been captured into a highly elliptical 2-year orbit around Jupiter (not the Sun!), probably during the early 1900s.

  • Tidal forces had broken the comet into 21 pieces during its (unseen) 1992 close approach to Jupiter.

  • Comet fragments stretched over a distance of more than 1 million km (3x the Earth-Moon distance).

A NASA Hubble Space Telescope image of comet P/Shoemaker-Levy 9 obtained on 17 May 1994. When the comet was observed, its train of 21 icy fragments stretched across 710 thousand miles (1.1 million km) of space, or 3 times the distance between Earth and the Moon. The comet was approximately 410 million miles (660 million km) from Earth when this photograph was taken.

Credit (image and some text): NASA, ESA, and H. Weaver and E. Smith (STScI) [link]

Between July 16 and 22, 1994, the fragments of Comet SL-9 collided with Jupiter.

Movie constructed from ground-based images of Jupiter in the infrared, showing the Great Red Spot (lighter oval on Jupiter), the Comet Shoemaker-Levy 9 impact (left), and Jupiter's moon Io (right).

Credit: Max Planck Institute for Astronomy [link]

Scientists worldwide watched Comet Shoemaker-Levy 9 slam into Jupiter in July 1994, representing the first time in human history that scientists were able to discover a celestial body in the sky, predict its impact, and then observe the comet's fiery plunge.

Although Jupiter clearly won the match, the largest planet in our solar system didn't emerge unscathed. In this Hubble Space Telescope image, taken nearly two hours after one of the fragments struck, the planet looks bruised. The impact area features a central dark spot 1,550 miles (2,500 km) in diameter, surrounded by rings that also are thousands of miles in diameter. Evidence suggests that the darkened spots on Jupiter and all the mighty plumes that soared into the planet's upper atmosphere occurred because of an object no more than one mile (1-1/2 km) in diameter.

One year after the comet crash, astronomers could still see vestiges of the bruises left on Jupiter by Comet Shoemaker-Levy 9. Interestingly, theorists had not predicted the bruising. In fact, scientists weren't certain of what they would see during the collision.

Credit (image and some text): NASA/STScI [link]

This mosaic of Hubble Space Telescope images shows the evolution of the Shoemaker-Levy 9 "G fragment" impact site on Jupiter. The images from lower right to upper left show: the impact plume (bottom edge of Jupiter) on 18 July 1994 about 5 minutes after the impact; the impact site at about 1.5 hours after impact; the impact site after evolution by the winds of Jupiter, along with the later "L fragment" impact site, 3 days after the G impact and 1.3 days after the L impact; and further evolution of the G and L impact sites due to winds and an additional impact (S) in the G vicinity, from 5 days after the G impact.

Credit (image and some text): JPL/NASA/STScI [link]

This has happened before, and will happen again…

These images show crater chains (catenas) on two of Jupiter’s moons that were likely caused by fragmented comet impacts.

View of a chain of craters named Enki Catena on Jupiter's moon, Ganymede. This chain of 13 craters probably formed by a comet which was pulled into pieces by Jupiter's gravity as it passed too close to the planet. Soon after this breakup, the 13 fragments crashed onto Ganymede in rapid succession. The image covers an area approximately 214 by 217 kilometers. The image was obtained on 5 April 1997 by NASA's Galileo spacecraft.

Credit (image and some text): NASA/JPL/Brown University [link]

This and other unusual crater chains on Jupiter's moon, Callisto, were formed by the impact of tidally disrupted comets. This chain, named Gipul Catena, is approximately 620 kilometers long, with craters up to 40 kilometers across (the scale bar at lower right is 100 km long).

Credit (image and some text): Lunar and Planetary Institute [link]
  • In 2009, another impact scar was discovered on Jupiter.

  • The impact itself was not observed.

  • The impactor was likely a 200-500 meter asteroid.

  • Additional small impact sites have been observed in 2010, 2012, and 2016.

This Hubble Space Telescope image, obtained on 23 July 2009, shows the site of an unobserved recent impact on Jupiter. The expanding spot marking the impact is twice the length of the United States. The spot looks strikingly similar to Comet Shoemaker-Levy 9's impact features. The details seen in the Hubble view shows lumpiness in the debris plume caused by turbulence in Jupiter's atmosphere. The impactor was estimated to be the size of several football fields. This is a natural color image of Jupiter as seen in visible light.

Credit: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team [link


2009 impactor size

  • NASA, 2011 (January 26) – “Asteroids ahoy! Jupiter scar likely from rocky body” [link]