Adrastea (moon)
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| Discovery | |||||||
|---|---|---|---|---|---|---|---|
| Discovered by | David C. Jewitt G. Edward Danielson |
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| Discovered on | July 8, 1979 | ||||||
| Orbital characteristics | |||||||
| Mean radius | 128,694 km (0.000860 AU) | ||||||
| Eccentricity | 0.0018 | ||||||
| Periapsis | 128,460 km (0.000859 AU) | ||||||
| Apoapsis | 128,930 km (0.000862 AU) | ||||||
| Revolution period | 0.29826 d (7 h 9.5 min) | ||||||
| Orbital circumference | 808,600 km (0.005 AU) | ||||||
| Orbital velocity | max: 31.435 km/s mean: 31.378 km/s min: 31.322 km/s |
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| Inclination | 2.22° (to the ecliptic) 0.00° (to Jupiter's equator) |
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| Is a satellite of | Jupiter | ||||||
| Physical characteristics | |||||||
| Mean diameter | 20 km (26×20×16 km) | ||||||
| Surface area | ~5300 km² | ||||||
| Volume | ~4400 km³ | ||||||
| Mass | 7.5×1015 kg | ||||||
| Mean density | 3.0 g/cm³ | ||||||
| Surface gravity | ~0.005 m/s2 (0.001 g) | ||||||
| Escape velocity | ~0.011 km/s | ||||||
| Rotation period | synchronous | ||||||
| Rotation velocity | 11 km/h | ||||||
| Axial tilt | zero | ||||||
| Albedo | 0.10 | ||||||
| Surface temp. |
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| Atmospheric pressure | 0 kPa | ||||||
Adrastea (ad'-rə-stee'-ə, IPA: [ˌædrəˈstiə], Greek Αδράστεια), or Jupiter XV, is the second of Jupiter's known moons (counting outward from the planet). It was discovered on Voyager 2 probe photographs taken in 1979 and received the designation S/1979 J 1 (IAUC 3454) after the discovery had been announced in Science (vol. 206, p. 951, November 23, 1979). In 1983 it was officially named after the mythological Adrastea, daughter of Jupiter and Ananke.
It is the smallest of the inner satellites of Jupiter.
Adrastea is the first natural satellite to be discovered through the use of images taken by an interplanetary spacecraft, rather than through telescopic photography.
Adrastea is inside Jupiter's planetary ring and may be the source of some of its material. Its orbit lies inside Jupiter's synchronous orbit radius, and as a result tidal forces are slowly causing its orbit to decay. It is also within Jupiter's Roche limit, but is dense or rigid enough to avoid tidal disruption.
[edit] See also
Inner satellites · Galilean moons · Themisto · Himalia group · Carpo · S/2003 J 12 · Ananke group · Carme group · Pasiphaë group · S/2003 J 2
Italics indicate individual ungrouped moons. See also Pronunciation key and Rings of Jupiter.
