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Jupiter's Smaller Moons A collection of pictures of Jupiter's smaller moons, taken by space probes.

So far with the help of telescopes and space probes, 79 moons have been discovered in Jupiter's orbit. For most of them the only pictures are small specs of light on images taken by telescopes, but five of the smaller moons have been photographed by space probes giving us a better idea of what these small objects look like. The picture to the left shows an artist's concept of the Galileo probe passing the small moon Amalthea / Source: NASA/Michael Carroll

Metis Metis is the innermost known moon of Jupiter. It has an irregular shape and measures 60×40×34 km across. Metis was discovered in 1979 in images taken by Voyager 1. Images taken by Galileo in 1996 and 1997 revealed some surface structures and gave a first insight into the irregular shape of the moon.

Image taken by Voyager 1 March 4, 1979 Source: NASA / Solarviews.com

Mosaic of Galileo-images taken between Nov. 1996 and June 1997 Source: NASA / Solarviews.com

Adrastea Adrastea is one of the four inner moons of Jupiter. It has an irregular shape and measures 20×16×14 km across. It orbits at the edge of Jupiter's Main Ring and is thought to be the main contributor of material to the Rings of Jupiter. Adrastea was the first moon in the Solar System to be discovered from images taken by an interplanetary spacecraft, rather than through a telescope. It was discovered during the analysis of pictures taken by Voyager 2, shortly before the discovery of Methis. In pictures taken by Galileo in 1996 and 1997 the moon's shape could be determined, but the images remain poor.

Image taken by Voyager 2 July 8, 1979 Source: NASA / Wikipedia

Galileo's best image of Adrastea December 19, 1996 from 658,100 km distance Source: NASA / Planetary Society

Amalthea Amalthea is the largest of the inner moons of Jupiter. It has an irregular shape and measures 250 × 146 × 128 km across. Amalthea was discovered on September 9, 1892 at Lick Observatory. It was the fifth Jovian moon discovered and last planetary satellite to be discovered by direct visual observation (as opposed to photographically). The Voyager probes delivered first images of this unusual reddish moon. Galileo produced a number of closeup images, allowing for the identification of surface features such as the craters Gaea (north, smaller) and Pan (south, larger).

Image taken by Voyager 1 from 425,000 km distance March 4, 1979 Source: NASA

Image taken by Galileo from 446,000 km distance August 12, 1999 Source: NASA / JPL

Thebe Thebe is one of the inner moons of Jupiter. It has an irregular shape and measures 116 x 98 x 84 km across. It is of reddish colour, and is thought to be similar to Amalthea, consisting of porous water ice with unknown amounts of other materials. Thebe was discovered in images taken by Voyager 1 on March 5, 1979. Galileo took a closeup image in 2000, identifying Thebe's surface structures including the impact crater Zethus, which has a diameter of 40 km.

Image taken by Galileo from 193,000 km distance January 4, 2000 Source: NASA / JPL

Himalia Himalia is the largest irregular satellite of Jupiter. It is the fifth largest known Jovian satellite. Himalia was discovered at the Lick Observatory on 3 December 1904. Only two spacecraft took distant pictures of Himalia, all just a few pixels across. Cassini, en route to Saturn, took pictures in November and December 2000 from a distance of 4.4 million kilometers. New Horizons, on its way to Pluto took pictures from a distance of 8 million kilometers in February and March 2007. No surface features were identified in these pictures, but the size of the moon was estimated as 150 x 120 km ±20 km.

Image taken by Cassini Source: NASA / JPL

It is about 665 million kilometers of empty space between the orbits of Jupiter and Saturn. The first human spacecraft to pass the ringed planet was Pioneer 11 in September 1979, followed by the Voyager probes in 1980 and 1981. From 2004 to 2009, the Cassini probe was in orbit around Saturn.

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