Discovered by Stephen Synnott
Date of Discovery 1980
Distance from Jupiter 222,000 km
Radius 55 x 45 km
Mass 8 × 10^20 g
Orbital Eccentricity 0.015
Orbital Inclination 0.8°
Orbital Period 0.6745 day
Rotational Period Synchronous
Density (g/cm3) ???
Mean Orbital Velocity 9.70 km/s
One of the four closest moons of Jupiter, orbiting within the circuit of Io. The others are Metis, Adrastea, and Amalthea. Due to their small size, they appear to be immune to the powerful tidal forces of Jupiter's formidable gravity. Larger bodies would be pulled apart. Poor Thebe has been repeatedly battered by speeding meteors racing towards Jupiter, and dust from these impacts is believed to be the source of Jupiter's Gossamer ring.
The same side of Thebe always faces Jupiter, as its rotation about its axis occurs once per revolution as our moon does. Thebe and Almathea are luckier than their sister moons, Metis and Adrastea. Those two will eventually be pulled into Jupiter because they are within the synchronous orbit radius.
This moon was discovered thanks to imagery from Voyager 1. The Galileo probe also snapped some nice pictures in 2000.