Jupiter’s Inner Moons

Jupiter currently has 79 known moons, but this number is still growing!  Most of these moons are very small and were probably once asteroids that Jupiter’s strong gravity pulled in. The four closest to Jupiter are Jupiter’s Inner Moons.
An illustration showing Jupiter's Inner Moons.
 

METIS

Stephen Synnott discovered this moon in 1979.  In Greek mythology, Metis was a Titaness who was the first wife of Jupiter.  Metis is the closest moon to the surface of Jupiter and sits within the planet’s main ring.

A telescope image of Metis, an inner moon of Jupiter.

NASA’s Galileo satellite took this photo from 292,600 miles away (that’s more than 20 planet Earth’s lined up)!

 
Metis is only 40km in diameter. As such, it is probably an asteroid that got caught by Jupiter’s immense gravity. Metis is very quick and orbits Jupiter in only 5 hours!
 

ADRASTEA

David Jewitt discovered Adrastea in 1979.  In mythology, Adrastea was the god who passed out rewards and punishments, she was also the daughter of Jupiter.  This moon is the second closest moon to the surface of Jupiter and completes an orbit in just 7 hours! 

A telescope image of Andrastea, an inner moon of Jupiter.

Adrastea is so small, there is no clear picture of it yet!

This moon is probably an asteroid that got caught by Jupiter’s immense gravity as well. It’s the smallest of Jupiter’s Inner Moons with a diameter of only 16 km! These moons are so small, you’d feel virtually weightless on them!
 

AMALTHEA

Edward Emerson Barnard discovered Amalthea in 1892. In Greek mythology, Amalthea nursed Jupiter as a young baby using goat’s milk. This is the third closest moon to the surface of Jupiter and completes an orbit every 12 hours.

A telescope image of Amalthea, an inner moon of Jupiter.

Amalthea is the reddest object in the solar system!

This moon is also probably an asteroid that got caught by Jupiter’s immense gravity. Amalthea is the largest of the inner moons with a diameter of 168 km.
 

THEBE

Stephen Synnott discovered the moon Thebe in 1980.  It’s named after a nymph, daughter of the river god Asopus. Thebe is the fourth known moon from the surface of Jupiter and completes an orbit every 16 hours.
 

A telescope image of Thebe, an inner moon of Jupiter.

Thebe and the other inner moons are too small to have strong gravity. That’s why they are in such weird shapes!

It too was probably an asteroid at one time and has a diameter of 98 km. If you, want to learn about Jupiter’s other moons, check out the Outer Moons and the Galilean Moons!

Other Great Resources

Moons of Jupiter – The Planets: https://theplanets.org/moons-of-jupiter/
(Video) Jupiter’s Moons – Crash Course Astronomy: https://www.youtube.com/watch?v=HaFaf7vbgpE&t=53s
Written by: Jesus Cervantes