Europa
(Jupiter II)
(well-known Jupiter moon)
Europa (Jupiter II) is one of the original four moons of Jupiter
found centuries ago (Galilean Moons),
the second outward from Jupiter and the smallest of these four,
and is the sixth outward of Jupiter's currently known moons.
Its radius is 1564 km (a quarter of Earth's), its mass is
4.5×1022 kg (about a hundredth of Earth's), with a mean density
about three times that of water (about 1/2 Earth's)
and oceans are suspected.
Europa's orbital period is 3.5 days and it is tidally locked.
Its orbit is in sync with Ganymede (1/2) and Io (2×).
Flyby observations of Europa have been made by
the Pioneer, Voyager, Galileo, and Juno missions.
Current theory presumes Europa has a subsurface ocean of water,
which is liquid due to
tidal heating (Europa is beyond the snow line, where
bodies can cool to the point where water would be frozen).
Evidence is that the surface is apparently water ice with
a smooth surface and high albedo.
Gravity measurements suggest the right mass distribution,
and the moon's effect on Jupiter's magnetic field suggests
an internal conductor such as salt water.
The moon's surface shows both characteristics of the Earth's crust
(e.g., few visible impact craters) and of the Earth's ice shelves.
The surface's markings are cracks, pits, and domes.
Patterns in the cracks suggest an analog to Earth's
crustal plates, showing subsumption bands,
regions where the pattern where surface features show
a discontinuity suggesting some surface was forced downward,
analogous to Earth subduction zones.
The surface also has regions with some color and there
is research and theories as to the cause.
Given the ocean, there is debate whether the ice constitutes
a thin shell (e.g., less than 10 km, making leaks and plumes
plausible) or a thick shell (e.g., tens of km or more), with some
thought that it has some of each.
The presumed oceans make Europa a candidate for life.
If the ocean is salty, a question of interest is what type of salt,
and whether it is in contact with a rocky core, which would
present the opportunity for some chemical reactions and
increase the likelihood of generation of molecules
associated with life.
(moon,Jupiter)
Further reading:
https://en.wikipedia.org/wiki/Europa_(moon)
https://en.wikipedia.org/wiki/Galilean_moons
http://hyperphysics.phy-astr.gsu.edu/hbase/Solar/Europa.html
http://astronomy.utfs.org/otto/solarsystem/eng/europa.htm
https://www.planetary.org/worlds/europa
https://science.nasa.gov/jupiter/moons/europa/europa-facts/
Redshift | Parsecs /Distance | Lightyears /Lookback Years | | |
~0 | 4.2AU | ~0ly | nearest | Europa |
~0 | 6.2AU | ~0ly | furthest | Europa |
|
Referenced by pages:
cryovolcano
Europa Clipper
Europa Lander
Galileo
Ganymede
Io
Jupiter
magnetic field
magnetic induction
moon
orbital resonance
Index