Adrastea [a-DRAS-tee-uh] is the second innermost known satellite of Jupiter. Adrastea was the daughter of Jupiter and Ananke and the distributor of rewards and punishments. Adrastea and Metis lie within Jupiter's main ring and may be the source of material for the ring. Very little is known about Adrastea.
Discovered by D. Jewitt & E. Danielson
Date of discovery 1979
Mass (kg) 1.91e+16
Mass (Earth = 1) 3.1961e-09
Radius (km) 12.5x10x7.5
Radius (Earth = 1) 1.9599e-03
Mean density (gm/cm^3) 4.5
Mean distance from Jupiter (km) 128,971
Rotational period (days) ?
Orbital period (days) 0.298260
Mean orbital velocity (km/sec) 31.45
Orbital eccentricity 0.0000
Orbital inclination (degrees) 0.0000
Escape velocity (km/sec) 0.0143
Visual geometric albedo 0.05
Magnitude (Vo) 19.1
|Views of Adrastea|
Galileo Image of Adrastea
This image of Adrastea was taken by Galileo's solid state imaging system between November 1996 and June 1997. Although Adrastea was discovered by Voyager, it was no more than a point of light on images. Adrastea orbits Jupiter in the zone between the planet's ring and the larger Galilean satellites. The longest dimension of Adrastea is approximately 20 kilometers (12 miles) across. (Courtesy of NASA/JPL)
This is the discovery image (FDS 20630.53) of Adrastea. It was taken by the Voyager spacecraft 23 hours before the closest approach to Jupiter. This image is a wide angle picture taken with a 15 second exposure. The range is 1.4 x 106 km. The faint line is the Jovian ring. Adrastea is a small dot above the arrow. The brighter dot to the left is a star. (Credit: Calvin J. Hamilton)
This image (FDS 20630.48) of Adrastea was taken 5 minutes earlier than the previous image. The exposure time was 96 seconds. The faint band is the Jovian ring and is smeared because of parallax and spacecraft motion. Adrastea is the bright line in the lower right. A star can be seen as a line in the upper left. Notice the difference in length and direction of the two lines. This image was used to verify that the spot in the previous image was indeed a satellite of Jupiter. (Credit: Calvin J. Hamilton)
Family Portrait of the Small Inner Satellites of Jupiter
These images, taken by Galileo's solid state imaging system between November 1996 and June 1997, provide the first ever "family portrait" of the four small, irregularly shaped moons that orbit Jupiter in the zone between the planet's ring and the larger Galilean satellites. The moons are shown in their correct relative sizes, with north approximately up in all cases. From left to right, arranged in order of increasing distance from Jupiter, are Metis (longest dimension is approximately 60 kilometers or 37 miles across), Adrastea (20 kilometers or 12 miles across), Amalthea (247 kilometers or 154 miles across), and Thebe (116 kilometers or 72 miles across). While Amalthea, the largest of these four tiny moons, was imaged by NASA's two Voyager spacecraft in 1979 with a resolution comparable to what is shown here, the new Galileo observations represent the first time that Metis, Adrastea, and Thebe have been seen as more than points of light. (Courtesy of NASA/JPL)
Jewitt, David C. et al. "Discovery of a New Jupiter Satellite." Science, Vol 206, 23 November 1979.
Synnott, S. P. "Orbits of the Small Inner Satellites of Jupiter." Icarus 58, 1984.
Jupiter Metis Amalthea
Copyright © 1997 by Calvin J. Hamilton. All rights reserved.