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| color=Marble white with reddish-brown streaks
| color=Marble white with reddish-brown streaks
| albedo=0.64<ref name=gal1/><ref name=solarviews/>
| albedo=0.64<ref name=gal1/><ref name=solarviews/>
| mfd=0.00024 G<ref name=Kivelson> M. G. Kivelson, K. K. Khurana, S. Joy, C. T. Russell, D. J. Southwood, R. J. Walker, C. Polanskey. "[http://www.sciencemag.org/cgi/content/abstract/276/5316/1239 Europa's Magnetic Signature: Report from Galileo's Pass on 19 December 1996]." ''Science'' 276(5316):1239-1241, May 23, 1997. <doi:10.1126/science.276.5316.1239> Accessed May 12, 2008.</ref>
| pmdm=9.13 * 10<sup>18</sup> N-m/T<ref name=calc/>
| cmdmmt=1.13 * 10<sup>22</sup> N-m/T<calc/>
| mdt=861.93 a<ref name=calc/>
| mhl=597.45 a<ref name=calc/>
}}'''Europa''' is the second innermost of the [[Galilean moons]] of [[Jupiter]], and also the smallest and lightest. Europa is named for the Phoenician princess who, according to legend, gave Europe its name, and was carried off to [[Crete]] by [[Zeus]], who had assumed the shape of a bull. Today Europa, more than any other object in the [[solar system]], continues to be the subject of speculation as to whether it harbors [[extraterrestrial life]].
}}'''Europa''' is the second innermost of the [[Galilean moons]] of [[Jupiter]], and also the smallest and lightest. Europa is named for the Phoenician princess who, according to legend, gave Europe its name, and was carried off to [[Crete]] by [[Zeus]], who had assumed the shape of a bull. Today Europa, more than any other object in the [[solar system]], continues to be the subject of speculation as to whether it harbors [[extraterrestrial life]].
Europa is likely surfaced with [[water]] ice and rock, with a 50-km-deep subterranean ocean deep to this, resting on a silicate floor that surrounds a metallic core. The surface has multiple dark streaks, some measuring 20 km broad. Their origin is uncertain but suspected to be volcanic or geothermal.<ref name=Arnett/>
Europa is likely surfaced with [[water]] ice and rock, with a 50-km-deep subterranean ocean deep to this, resting on a silicate floor that surrounds a metallic core. The surface has multiple dark streaks, some measuring 20 km broad. Their origin is uncertain but suspected to be volcanic or geothermal.<ref name=Arnett/>
Detailed measurements by the spacecraft Galileo (December 19, 1996<ref name=Kivelson/>) revealed that Europa does have its own magnetic field, though it is very weak—only 0.24 milligauss at its equator. This corresponds to a magnetic dipole moment of 9.13 * 10<sup>18</sup> N-m/T. Europa's mass suggests a magnetic dipole moment at creation of 1.13 * 10<sup>22</sup> N-m/T, according to the [[Russell Humphreys]] magnetic-field model.<ref name=Humphreys>Humphreys, D. R. "[http://www.creationresearch.org/crsq/articles/21/21_3/21_3.html The Creation of Planetary Magnetic Fields]." ''[[Creation Research Society Quarterly]]'' 21(3), December 1984. Accessed April 29, 2008.</ref> Thus the decay time for this field is 861.93 Julian years, and the half-life is 597.45 Julian years. All of the above are consistent with Io having a small but significantly conductive core and possibly a liquid ocean holding electrolytes in solution.
The [[Hubble Space Telescope]] has detected evidence of an "atmosphere" at pressure 10<sup>-11</sup> bar, containing [[oxygen]].<ref name=Arnett/><ref name=planetsoc/> Most authorities ''do not'' suggest that this oxygen is biotic. Rather, they suggest that sunlight and the charged particles of Jupiter's radiation belt cause the water ice on Europa to vaporize and then to split into [[hydrogen]] and oxygen--and the hydrogen, being much lighter, tends to escape Europa's light gravity (0.135 ''g'') and leave the oxygen.<ref name=Arnett/><ref name=planetsoc/>
The [[Hubble Space Telescope]] has detected evidence of an "atmosphere" at pressure 10<sup>-11</sup> bar, containing [[oxygen]].<ref name=Arnett/><ref name=planetsoc/> Most authorities ''do not'' suggest that this oxygen is biotic. Rather, they suggest that sunlight and the charged particles of Jupiter's radiation belt cause the water ice on Europa to vaporize and then to split into [[hydrogen]] and oxygen--and the hydrogen, being much lighter, tends to escape Europa's light gravity (0.135 ''g'') and leave the oxygen.<ref name=Arnett/><ref name=planetsoc/>