Europa (moon)
Europa
Europa, as seen by the Galileo spacecraft
Discovery
Discovered by
G. Galilei
S. Marius
Discovery date
January 7, 1610
Designations
Alternate name
Jupiter II
Adjective
Europan
Orbital characteristics[1]
Epoch January 8, 2004
Periapsis
664 862 km[2]
Apoapsis
676 938 km[2]
Mean orbit radius
670 900 km[3]
Eccentricity
0.009[3]
Orbital period
3.551 181 d[3]
Average
orbital speed
13.740 km/s[3]
Inclination
0.470° (to Jupiter’s
equator)[3]
Satellite of
Jupiter
Physical characteristics
Mean radius
1569 km (0.245
Earths)[3]
Surface area
3.09 × 107 km2 (0.061
Earths)[4]
Volume
1.593 × 1010 km3 (0.015
Earths)[4]
Mass
4.80 × 1022 kg (0.008
Earths)[3]
Mean density
3.01 g/cm3[3]
Equatorial
surface gravity
1.314 m/s2 (0.134 g)[2]
Escape velocity
2.025 km/s[2]
Rotation period
Synchronous[5]
Axial tilt
0.1°[6]
Albedo
0.67 ± 0.03[7]
Surface temp.
Surface
min
mean max
~50
K[8]
102 K 125 K
Apparent
magnitude
5.29 (opposition)[7]
Atmosphere
Surface pressure
0.1 µPa (10-12 bar)[9]
Europa (pronounced /jʊˈroʊpə/[10]
listen ;
or as Greek Ευρώπη) is the sixth moon of the
planet Jupiter. Europa was discovered in
1610 by Galileo Galilei (and possibly inde-
pendently by Simon Marius), and named
after a mythical Phoenician noblewoman,
Europa, who was courted by Zeus and be-
came the queen of Crete. It is the smallest of
the four Galilean moons.
At just over 3,100 kilometres (1,900 mi) in
diameter, Europa is slightly smaller than
Earth’s Moon and is the sixth-largest moon in
the Solar System. Though by a wide margin
the least massive of the Galilean satellites, its
mass nonetheless significantly exceeds the
combined mass of all moons in the Solar Sys-
tem smaller than itself.[11] It is primarily
made of silicate rock and likely has an iron
core. It has a tenuous atmosphere composed
primarily of oxygen. Its surface is composed
of ice and is one of the smoothest in the Solar
System. This young surface is striated by
From Wikipedia, the free encyclopedia
Europa (moon)
1
cracks and streaks, while craters are relat-
ively infre