Proteus: Neptune Satellite
Proteus is the second largest moon of Neptune behind the mysterious Triton. Image source: (1)
Proteus with a diameter of 440 km, is the largest of six small moons that orbit in the interior and around the rings of Neptune. It is also known as Neptune VIII. It was discovered in 1989 by the space probe Voyager 2, and orbits around the planet in 1,122 days, at a distance of 177,650 km.
Proteus of irregular form, is a very sombrío object, resembling the soot, reflects only 10% of the light who strikes it. Proteus is the name of marine god of Greek mythology that could change form at will, son of Poseidón.
Its structure is very porous, low density, and shows no signs of geological activity. In Proteus there is an extraordinarily large crater and, according to scientists, the impact of a body of that magnitude should have pulverized the satellite. As it is not, two theories have been elaborated that try to explain this mystery. One is that Proteus' extremely porous structure saved it from destruction. The other than the satellite was before the impact much larger, being what we see the remains of after the explosion.
More details here: Proteus
A simulated view of Proteus orbiting Neptune. Image source: (2)
