Io (moon)
Io is a moon of the planet Jupiter. It is Jupiter's third biggest moon with a diameter of 3642 km, slightly bigger than Earth's moon.
 Galileo spacecraft true-color image of Io. The dark spot just left of the center is the erupting volcano Prometheus. The whitish plains on either side of it are coated with volcanically deposited sulfur dioxide frost, whereas the yellower regions contain a higher proportion of sulfur. | |||||||||
| Discovery | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Discovered by | Galileo Galilei | ||||||||
| Discovery date | 8 January 1610 | ||||||||
| Designations | |||||||||
| Pronunciation | /ˈaɪ.oʊ/[1] | ||||||||
| Jupiter I | |||||||||
| Adjectives | Ionian | ||||||||
| Orbital characteristics | |||||||||
| Periapsis | 420000 km (0.002807 AU) | ||||||||
| Apoapsis | 423400 km (0.002830 AU) | ||||||||
Mean orbit radius | 421700 km (0.002819 AU) | ||||||||
| Eccentricity | 0.0041 | ||||||||
| 1.769137786 d (152853.5047 s, 42.45930686 h) | |||||||||
Average orbital speed | 17.334 km/s | ||||||||
| Inclination | 0.05° (to Jupiter's equator) 2.213° (to the ecliptic) | ||||||||
| Satellite of | Jupiter | ||||||||
| Physical characteristics | |||||||||
| Dimensions | 3,660.0 × 3,637.4 × 3,630.6 km[2] | ||||||||
Mean radius | 1821.6±0.5 km (0.286 Earths)[3] | ||||||||
| 41910000 km2 (0.082 Earths) | |||||||||
| Volume | 2.53×1010 km3 (0.023 Earths) | ||||||||
| Mass | (8.931938±0.000018)×1022 kg (0.015 Earths)[3] | ||||||||
Mean density | 3.528±0.006 g/cm3[3] | ||||||||
| 1.796 m/s2 (0.183 g) | |||||||||
| 0.3755±0.0045[4] (estimate) | |||||||||
| 2.558 km/s | |||||||||
| synchronous | |||||||||
Equatorial rotation velocity | 271 km/h | ||||||||
| Albedo | 0.63±0.02[3] | ||||||||
| |||||||||
| 5.02 (opposition)[5] | |||||||||
| Atmosphere | |||||||||
Surface pressure | 5 to 40 nbar | ||||||||
| Composition by volume | 90% sulfur dioxide | ||||||||
Io has about 400 active volcanos. It is the most volcanically active body in the Solar System. This is due to tidal heating because of friction between Jupiter and the other moons, Callisto, Ganymede, and Europa. [7]Volcanoes erupt massive volumes of silicate lava, sulphur and sulphur dioxide. This constantly changes Io's appearance.
The picture of Jupiter's moon Io was produced by combining the best images from both the Voyager 1 and Galileo Missions. Superbly detailed Voyager 1 images cover longitudes from 240 W to 40 W and the nearby southern latitudes.
Io has highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water of any known astronomical object in the Solar System.
Due to the same tidal locking that makes the Moon have the same side always facing Earth, Io always has the same side facing Jupiter. Io is a prolate spheroid, pulled out of round by tidal stress from Jupiter’s gravity.
Io (moon) Media
- Io comparison with Earth and Moon.png
Size comparison between Io (lower left), the Moon (upper left) and Earth
- Medicean Stars.png
Io as part of the Medician stars, for the first time reported and drawn in the Sidereus Nuncius (the 'starry messenger'), 1610. The moons are drawn in changing positions.
- Io VGR South polar color mosaic.jpg
Voyager 1 mosaic covering Io's south polar region. This includes two of Io's ten highest peaks, the Euboea Montes at upper extreme left and Haemus Mons at bottom.
- PIA01667-Io's Pele Hemisphere After Pillan Changes.jpg
Enhanced-color Galileo image showing a dark spot (just lower-left of center, interrupting the red ring of short-chain sulfur allotropes deposited by Pele) produced by a major eruption at Pillan Patera in 1997
Io as seen by JunoCam on 3 February 2024. Its night side is illuminated by the reflected sunlight from Jupiter.
- Galilean moon Laplace resonance animation 2.gif
Animation of the Laplace resonance of Io, Europa and Ganymede (conjunctions are highlighted by color changes)
- Jupiter's magnetosphere in the vicinity of the Galilean satellites.jpg
Schematic of Jupiter's magnetospheric plasma environment, including the plasma torus around Jupiter, the neutral clouds around the moons, and the flux tube between Jupiter and its moons. Objects are not to scale.
- Io diagram.svg
Model of the possible interior composition of Io with various features labelled.
- Io from Galileo and Voyager missions.jpg
- IofromGalileoandVoyagermissions
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References
- ↑ EYE-oh, or as Greek: Ἰώ
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ 3.0 3.1 3.2 3.3 Yeomans, Donald K. (13 July 2006). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics.
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ "Classic Satellites of the Solar System". Observatorio ARVAL. Archived from the original on 25 August 2011. Retrieved 28 September 2007.
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).