Europa (moon)

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Europa
Europa-moon.jpg
Europa, as seen by the Galileo spacecraft
Discovery
Discovered byG. Galilei
Marius, Simon
Discovery dateJanuary 7, 1610
Names
Other namesJupiter II
AdjectiveEuropan
Orbit [3]
Reference date January 8, 2004
Shortest distance from what it orbits664 862 km[1]
Longest distance from what it orbits676 938 km[1]
Avgdistance from the center of its orbital path670 900 km[2]
How long it takes to complete an orbit3.551 181 d[2]
Average speed13.740 km/s[2]
Angle above the reference plane
("inclination")
0.470° (to Jupiter's equator)[2]
What it orbitsJupiter
Size and other qualities
Average radius1569 km (0.245 Earths)[2]
Surface area3.09×107 km2 (0.061 Earths)[4]
Volume1.593×1010 km3 (0.015 Earths)[4]
Mass4.80×1022 kg (0.008 Earths)[2]
Average density3.01 g/cm3[2]
Surface gravity1.314 m/s2 (0.134 g)[1]
Escape velocity2.025 km/s[1]
Rotation periodSynchronous[5]
Angle at which it turns
(in relation to its orbit)
0.1°[6]
How much light it reflects0.67 ± 0.03[7]
Surface temp. Min. Avg. Max.
Surface ~50 K[8] 102 K 125 K
Seeming brightness
("apparent magnitude")
5.29 (opposition)[7]
Atmosphere
Pressure0.1 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.

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' until the middle of the 20th century.

References[change | change source]

  1. 1.0 1.1 1.2 1.3 Calculated on the basis of other parameters
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 "Overview of Europa Facts". NASA. Retrieved 2007-12-27.
  3. "JPL HORIZONS solar system data and ephemeris computation service". Solar System Dynamics. NASA, Jet Propulsion Laboratory. Retrieved 2007-08-10.
  4. 4.0 4.1 Using the mean radius
  5. See Geissler et al. (1998) in orbit section for evidence of non-synchronous orbit.
  6. 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. 7.0 7.1 Yeomans, Donald K. (2006-07-13). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics. Retrieved 2007-11-05.
  8. McFadden, Lucy-Ann; Weissman, Paul; and Johnson, Torrence (2007). The Encyclopedia of the Solar System. Elsevier. p. 432.CS1 maint: Multiple names: authors list (link)
  9. 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.CS1 maint: Multiple names: editors list (link)
  10. Greenberg, Richard; Europa: The Ocean Moon: Search for an Alien Biosphere, Springer Praxis Books, 2005

Other Websites[change | change source]