Changes

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/>

[[Image:Europa sulfuric.jpg|150 px|right]]More recently, [[sulfuric acid]] has been found on Europa.<ref name=acid>"[http://science.nasa.gov/newhome/headlines/ast30sep99_1.htm Sulfuric Acid Found on Europa]." ''Science@NASA'', September 30, 1999. Accessed February 29, 2008.</ref> This might explain the red striations; they might be composed largely of elemental sulfur.

[[Image:Europa sulfuric.jpg|150 px|right]]More recently, [[sulfuric acid]] has been found on Europa.<ref name=acid>"[https://science.nasa.gov/newhome/headlines/ast30sep99_1.htm Sulfuric Acid Found on Europa]." ''Science@NASA'', September 30, 1999. Accessed February 29, 2008.</ref> This might explain the red striations; they might be composed largely of elemental sulfur.

=== Controversy over Europa's surface ===

=== Controversy over Europa's surface ===