Europa (moon)
Europa, as seen by the Galileo spacecraft
|
|||||||||
| Discovery | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Discovered by | G. Galilei Marius, Simon |
||||||||
| Discovery date | January 7, 1610 | ||||||||
| Names | |||||||||
| Other names | Jupiter II | ||||||||
| Adjective | Europan | ||||||||
| Orbit [3] | |||||||||
| Reference date January 8, 2004 | |||||||||
| Shortest distance from what it orbits | 664 862 km[1] | ||||||||
| Longest distance from what it orbits | 676 938 km[1] | ||||||||
| Avg. distance from the center of its orbital path | 670 900 km[2] | ||||||||
| How long it takes to complete an orbit | 3.551 181 d[2] | ||||||||
| Average speed | 13.740 km/s[2] | ||||||||
| Angle above the reference plane ("inclination") |
0.470° (to Jupiter's equator)[2] | ||||||||
| What it orbits | Jupiter | ||||||||
| Size and other qualities | |||||||||
| Average radius | 1569 km (0.245 Earths)[2] | ||||||||
| Surface area | 3.09×107 km2 (0.061 Earths)[4] | ||||||||
| Volume | 1.593×1010 km3 (0.015 Earths)[4] | ||||||||
| Mass | 4.80×1022 kg (0.008 Earths)[2] | ||||||||
| Average density | 3.01 g/cm3[2] | ||||||||
| Surface gravity | 1.314 m/s2 (0.134 g)[1] | ||||||||
| Escape velocity | 2.025 km/s[1] | ||||||||
| Rotation period | Synchronous[5] | ||||||||
| Angle at which it turns (in relation to its orbit) |
0.1°[6] | ||||||||
| How much light it reflects | 0.67 ± 0.03[7] | ||||||||
|
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| Seeming brightness ("apparent magnitude") |
5.29 (opposition)[7] | ||||||||
| Atmosphere | |||||||||
| Pressure | 0.1 µPa (10-12 bar)[9] | ||||||||
Europa is a large moon of the planet Jupiter. It is a little smaller than Earth's Moon and it is the sixth-largest moon in the solar system.
Europa's diameter is about 3000 kilometers. It probably has an iron core, and an atmosphere that's mostly oxygen. The surface is icy and very smooth. There are not a lot of craters, but there are some cracks and lines. Because the surface is so young and smooth, scientists believe that there is a liquid ocean under the surface, a so called subsurface ocean, and that it is kept warm by tidal heating.[10] In other words, Jupiter's strong gravitational pull on Europa makes it warm.[11]
The moon Europa was found by Simon Marius in December 1609. Galileo Galilei first saw the moon in January 1610 (he did not know Marius had found it). Simon Marius was the one who had the idea of the name 'Europa'.
The moon Europa is named after a princess from Greek mythology who became the first queen of Crete. However, people usually called Europa 'Jupiter II' till the middle of the 20th century.
Life on Europa[change | change source]
There may be alien life in Europa's subsurface ocean, life similar to that of the Antarctic Lake Vostok or in Earth's deep oceans. There is no proof, but it is possible.
At least three things are necessary for life to develop - water, organic compounds, and heat.[11] Europa has water and heat, and organic compounds can easily be found throughout the Solar System.
References[change | change source]
- ↑ 1.0 1.1 1.2 1.3 Calculated on the basis of other parameters
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 "Overview of Europa Facts". NASA. Retrieved 2007-12-27.
- ↑ "JPL HORIZONS solar system data and ephemeris computation service". Solar System Dynamics. NASA, Jet Propulsion Laboratory. Retrieved 2007-08-10.
- ↑ 4.0 4.1 Using the mean radius
- ↑ See Geissler et al. (1998) in orbit section for evidence of non-synchronous orbit.
- ↑ Bills, Bruce G. (2005). "Free and forced obliquities of the Galilean satellites of Jupiter". Icarus 175: 233–247. doi:10.1016/j.icarus.2004.10.028. http://adsabs.harvard.edu/abs/2005Icar..175..233B.
- ↑ 7.0 7.1 Yeomans, Donald K. (2006-07-13). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics. Retrieved 2007-11-05.
- ↑ McFadden, Lucy-Ann; Weissman, Paul; and Johnson, Torrence (2007). The Encyclopedia of the Solar System. Elsevier. p. 432.
- ↑ McGrath (2009). "Atmosphere of Europa". In Pappalardo, Robert T.; McKinnon, William B.; and Khurana, Krishan K. Europa. University of Arizona Press. ISBN 0-816-52844-6.
- ↑ Greenberg, Richard; Europa: The Ocean Moon: Search for an Alien Biosphere, Springer Praxis Books, 2005
- ↑ 11.0 11.1 Earth Science. United States of America: Holt, Rinehart and Winston. 2001. p. 211. ISBN 0-03-055667-8.
