Moons of Jupiter
Since the discovery of Jupiter's four largest moons (satellites) in 1610 by Galileo
Galilee, the number of discovered moons orbiting Jupiter has continued
to increase. When an astronomer discovers a new moon orbiting Jupiter,
it is reported to the International Astronomical Union, which gives it a
temporary name until its orbit is confirmed. Once confirmed, the moon
is given an appropriate name and added to the list of officially
recognized moons. There are currently 50 of such officially named moons (satellites)
with another 17 "temporary" moons (satellites) awaiting orbit confirmation.
An illustration of the 4 Galilean moons.
Jupiter's four largest moons are Io, Europa, Ganymede and Callisto.
Their discovery provided the crucial evidence that planets in the Solar
System orbit the Sun rather than the Earth. It was also the first time
that a moon was discovered orbiting a planet other than the Earth.
Io is the third largest of Jupiter's moons and fifth in distance from
the planet. It is only slightly larger (diameter 3,643.2 km) than the
Earth's moon (3,474 km). It is characterized by the tremendous amount of
volcanic activity on its surface. Io is the most volcanically active
object in the Solar System. Its surface is covered by a layer of sulfur
and more than a dozen volcanoes release hot silicate magma. Io orbits
Jupiter once every 42.46 hours (1.76 Earth days).
Europa is the smallest of the four Galilean moons and is sixth in orbit
from the planet. Its diameter of 3,121.6 km is slightly smaller than the
Earth's moon. Europa's unique feature is its surface of water ice.
There is also evidence to suggest that this icy surface may be covering
an ocean of either water or slush beneath it. Europa's watery condition
is important information because it could possibly support some life
forms. Europa orbits Jupiter once every 3.55 days.
Ganymede is the largest of the four Galilean moons and is seventh in
orbit from the planet. Ganymede also holds the distinction of being the
largest moon in the Solar System, even larger than the planet Mercury.
It is the only moon with its own internally generated magnetic field.
Its surface is made of silicate rock and water ice and is characterized
by dark regions of craters and light regions of grooves and ridges.
Ganymede completes one orbit around Jupiter in 7.15 days.
Callisto is the farthest of the Galilean moons. It is roughly the size
of Mercury (4,820.6 km vs. 4,879.4 km) but is only one third of the
planet's mass. Callisto's ancient and heavily crated surface is a
mixture of unknown rocky material and water ice in approximately equal
parts. Callisto completes one orbit around Jupiter in 16.68 days.
List of Jupiter's 67 Moons
Name |
Distance from Jupiter (km) |
Days for 1 full Orbit around Jupiter |
Diameter (km) |
Year Discovered |
Group |
Metis | 128,100 | 0.3 | 44 | 1979 | Amalthea |
Adrastea | 128,900 | 0.3 | 16 | 1979 | Amalthea |
Amalthea | 181,400 | 0.5 | 168 | 1892 | Amalthea |
Thebe | 221,900 | 0.7 | 98 | 1979 | Amalthea |
Io | 421,800 | 1.8 | 3,643 | 1610 | Galilean |
Europa | 671,100 | 3.6 | 3,122 | 1610 | Galilean |
Ganymede | 1,070,400 | 7.2 | 5,262 | 1610 | Galilean |
Callisto | 1,882,700 | 16.7 | 4,821 | 1610 | Galilean |
Themisto | 7,507,000 | 130.0 | 9 | 2000 | Themisto |
Leda | 11,165,000 | 240.9 | 18 | 1974 | Himalia |
Himalia | 11,461,000 | 250.6 | 160 | 1904 | Himalia |
Lysithea | 11,717,000 | 259.2 | 38 | 1938 | Himalia |
Elara | 11,741,000 | 259.6 | 78 | 1905 | Himalia |
S/2000 J11 | 12,555,000 | 287.0 | 4 | 2000 | Himalia |
Carpo | 16,989,000 | 456.1 | 3 | 2003 | Carpo |
Euporie | 19,302,000 | 550.7 | 2 | 2001 | Ananke |
Orthosie | 20,721,000 | 622.6 | 2 | 2001 | Ananke |
Euanthe | 20,799,000 | 620.6 | 3 | 2001 | Ananke |
Thyone | 20,940,000 | 627.3 | 4 | 2001 | Ananke |
Mneme | 21,069,000 | 620.0 | 2 | 2003 | Ananke |
Harpalyke | 21,105,000 | 623.3 | 4 | 2000 | Ananke |
Hermippe | 21,131,000 | 633.9 | 4 | 2001 | Ananke |
Praxidike | 21,147,000 | 625.3 | 7 | 2000 | Ananke |
Thelxinoe | 21,162,000 | 628.1 | 2 | 2003 | Ananke |
Iocaste | 21,269,000 | 631.5 | 5 | 2000 | Ananke |
Ananke | 21,276,000 | 610.5 | 28 | 1951 | Ananke |
Arche | 22,931,000 | 723.9 | 3 | 2002 | Carme |
Pasithee | 23,096,000 | 719.5 | 2 | 2001 | Carme |
Herse | 23,097,000 | 715.4 | 2 | 2003 | Carme |
Chaldene | 23,179,000 | 723.8 | 4 | 2000 | Carme |
Kale | 23,217,000 | 729.5 | 2 | 2001 | Carme |
Isonoe | 23,217,000 | 725.5 | 4 | 2000 | Carme |
Aitne | 23,231,000 | 730.2 | 3 | 2001 | Carme |
Erinome | 23,279,000 | 728.3 | 3 | 2000 | Carme |
Taygete | 23,360,000 | 732.2 | 5 | 2000 | Carme |
Carme | 23,404,000 | 702.3 | 46 | 1938 | Carme |
Kalyke | 23,583,000 | 743.0 | 5 | 2000 | Carme |
Eukelade | 23,661,000 | 746.4 | 4 | 2003 | Carme |
Kallichor | 24,043,000 | 764.7 | 2 | 2003 | Carme |
Helike | 21,263,000 | 634.8 | 4 | 2003 | Pasiphae |
Eurydome | 22,865,000 | 717.3 | 3 | 2001 | Pasiphae |
Autonoe | 23,039,000 | 762.7 | 4 | 2001 | Pasiphae |
Sponde | 23,487,000 | 748.3 | 2 | 2001 | Pasiphae |
Pasiphae | 23,624,000 | 708.0 | 58 | 1908 | Pasiphae |
Megaclite | 23,806,000 | 752.8 | 6 | 2000 | Pasiphae |
Sinope | 23,939,000 | 724.5 | 38 | 1914 | Pasiphae |
Hegemone | 23,947,000 | 739.6 | 3 | 2003 | Pasiphae |
Aoede | 23,981,000 | 761.5 | 4 | 2003 | Pasiphae |
Callirrho | 24,102,000 | 758.8 | 7 | 1999 | Pasiphae |
Cyllene | 24,349,000 | 737.8 | 2 | 2003 | Pasiphae |
Kore | 24,543,000 | 779.2 | 2 | 2003 | Pasiphae |
S/2003 J2 | 28,570,410 | 982.5 | 2 | 2003 | No Group |
S/2003 J3 | 18,339,885 | 504.0 | 2 | 2003 | No Group |
S/2003 J4 | 23,257,920 | 723.2 | 2 | 2003 | No Group |
S/2003 J5 | 24,084,180 | 759.7 | 4 | 2003 | No Group |
S/2003 J9 | 22,441,680 | 683.0 | 1 | 2003 | No Group |
S/2003 J10 | 24,249,600 | 767.0 | 2 | 2003 | No Group |
S/2003 J12 | 19,002,480 | 533.3 | 1 | 2003 | No Group |
S/2003 J15 | 22,000,000 | 668.4 | 2 | 2003 | No Group |
S/2003 J16 | 21,000,000 | 595.4 | 2 | 2003 | No Group |
S/2003 J18 | 20,700,000 | 606.3 | 2 | 2003 | No Group |
S/2003 J19 | 22,800,000 | 701.3 | 2 | 2003 | No Group |
S/2003 J23 | 24,055,500 | 759.7 | 2 | 2003 | No Group |
S/2010 J1 | 23,314,335 | 723.2 | 2 | 2010 | No Group |
S/2010 J2 | 20,307,150 | 588.1 | 1 | 2010 | No Group |
S/2011 J1 | 20,155,290 | 580.7 | 1 | 2011 | No Group |
S/2011 J2 | 23,329,710 | 726.8 | 1 | 2011 | No Group |