Changes

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&mdash;only 2.4 milligauss at its equator. This corresponds to a magnetic dipole moment of 9.13 * 10¹⁸ N-m/T. Europa's mass suggests a magnetic dipole moment at creation of 1.13 * 10²² 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.

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&mdash;only 2.4 milligauss at its equator. This corresponds to a magnetic dipole moment of 9.13 * 10¹⁸ N-m/T. (The dipole is oblique to the currents of the magnetic field of Jupiter, and thus it is more likely internal than external.<ref name=Kivelson/>) Europa's mass suggests a magnetic dipole moment at creation of 1.13 * 10²² 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^-11 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^-11 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/>