Metis

Metis, also known as Jupiter XVI, is the innermost irregular-shaped satellite belonging to the outer planet of Jupiter. It is one of the three satellites known in the Solar System to orbit its home planet in less time than its home planet's day, the other being Adrastea, another satellite belonging to Jupiter, and Mars' largest moon, Phobos. This satellite was discovered by Stephen P. Synnott on March 4, 1979.

Orbit
Metis orbits in the inner regions of Jupiter's main ring and is one of the planets in the Solar System to orbit its home planet in less time than its home planet's day. Tidal forces, which is a gravitational pull on a planet caused by a satellite's inner ocean, keep this planet in a constant orbit around Jupiter. Since this pull is so strong, however, Metis is predicted to collide with Jupiter in the next few million years.

Metis is one of the three moons in the Solar System that orbit its home planet in less time than the planet's day. The others are another one of Jupiter's satellites, Adrastea, and Mars' largest satellite, Phobos.

Formation
Metis has color spectra that match that of C or D-type asteroids, which are populous in the neighboring Asteroid belt. It is believed Metis was a stray asteroid that was pulled in by Jupiter's gravitational pull.

Surface
Metis' surface is mostly consisted of valleys and very few craters. The surface color is grey, which matches those of C-type asteroids, yet infrared spectrums show signs of D-type asteroids, which make up the middle region of the Asteroid belt.