Europa, as seen by the Galileo spacecraft
|Discovered by||G. Galilei
|Discovery date||January 7, 1610|
|Alternative names||Jupiter II|
|Epoch January 8, 2004|
|Periapsis||664 862 km|
|Apoapsis||676 938 km|
|Mean orbit radius||670 900 km|
|Orbital period||3.551 181 d|
|Average orbital speed||13.740 km/s|
|Inclination||0.470° (to Jupiter's equator)|
|Mean radius||1569 km (0.245 Earths)|
|Surface area||3.09×107 km2 (0.061 Earths)|
|Volume||1.593×1010 km3 (0.015 Earths)|
|Mass||4.80×1022 kg (0.008 Earths)|
|Mean density||3.01 g/cm3|
|Equatorial surface gravity||1.314 m/s2 (0.134 g)|
|Escape velocity||2.025 km/s|
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 ocean, and that it is kept warm by tidal heating. In other words, Jupiter's strong gravitational pull on Europa makes it warm.
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.'
Life on Europa [change]
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.
- Calculated on the basis of other parameters
- "Overview of Europa Facts". NASA. http://www2.jpl.nasa.gov/galileo/europa/. Retrieved 2007-12-27.
- "JPL HORIZONS solar system data and ephemeris computation service". Solar System Dynamics. NASA, Jet Propulsion Laboratory. http://ssd.jpl.nasa.gov/horizons.cgi. Retrieved 2007-08-10.
- 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.
- Yeomans, Donald K. (2006-07-13). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics. http://ssd.jpl.nasa.gov/?sat_phys_par. Retrieved 2007-11-05.
- Greenberg, Richard; Europa: The Ocean Moon: Search for an Alien Biosphere, Springer Praxis Books, 2005
- Earth Science. United States of America: Holt, Rinehart and Winston. 2001. pp. 211. ISBN 0-03-055667-8.
Other Websites [change]