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
Size comparison between Io (lower left), the Moon (upper left) and Earth
Galileo Galilei, the discoverer of Io
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.
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
The Cassini-Huygens mission's view of Io and Jupiter on 1 January 2001
Global image of Jupiter's moon Io acquired by Juno's JunoCam camera on 30 December 2023
Animation of the Laplace resonance of Io, Europa and Ganymede (conjunctions are highlighted by color changes)
Schematic of Jupiter's magnetosphere and the components influenced by Io (near the center of the image): the plasma torus (in red), the neutral cloud (in yellow), the flux tube (in green), and magnetic field lines (in blue).
The Jupiter - Io System and Interaction(artwork; 15 July 2021)
Model of the possible interior composition of Io with various features labelled.
Loki Patera on moon Io (artist's concept; animation; 0:18)
"Steeple Mountain" on moon Io(animation; JunoCam; 0:14; 18 April 2024)
References
- ↑ EYE-oh, or as Greek: Ἰώ
- ↑ Thomas, P. C.; et al. (1998). "The Shape of Io from Galileo Limb Measurements". Icarus. 135 (1): 175–180. Bibcode:1998Icar..135..175T. doi:10.1006/icar.1998.5987.
- ↑ 3.0 3.1 3.2 3.3 Yeomans, Donald K. (13 July 2006). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics.
- ↑ Showman, Adam P.; Malhotra, Renu (October 1999). "The Galilean Satellites". Science. 286 (5437): 77–84. doi:10.1126/science.286.5437.77. PMID 10506564.
- ↑ "Classic Satellites of the Solar System". Observatorio ARVAL. Archived from the original on 25 August 2011. Retrieved 28 September 2007.
- ↑ Rathbun, J. A.; Spencer, J.R.; Tamppari, L.K.; Martin, T.Z.; Barnard, L.; Travis, L.D. (2004). "Mapping of Io's thermal radiation by the Galileo photopolarimeter-radiometer (PPR) instrument". Icarus. 169 (1): 127–139. Bibcode:2004Icar..169..127R. doi:10.1016/j.icarus.2003.12.021.
- ↑ Lopes, Rosaly M. C.; Kamp, Lucas W.; Smythe, William D.; Mouginis-Mark, Peter; Kargel, Jeff; Radebaugh, Jani; Turtle, Elizabeth P.; Perry, Jason; Williams, David A.; Carlson, R. W.; Douté, S. (2004-05-01). "Lava lakes on Io: observations of Io's volcanic activity from Galileo NIMS during the 2001 fly-bys". Icarus. 169: 140–174. doi:10.1016/j.icarus.2003.11.013. ISSN 0019-1035.