Neptune’s moon Triton.
It gets as cold as -235°C. But that isn't what makes it so weird.
Neptune has 14 moons. With the exception of Titan, all the moons are very small, and come in two varieties— regular and irregular.
The regular ones orbit close to the planet, and irregular ones are generally farther from Neptune, with all sorts of crazy orbits..
And then there's Triton. It was discovered by amateur astronomer William Lassell, who, in 1846, spotted the moon a mere 17 days after the discovery of Neptune itself.
There are many reasons that make it strange.
For one, Triton is big. The 7th largest moon of Solar System. It’s over 200 times bigger than all the other moons of Neptune combined.
Second, it's one of the irregular moons, for it orbits the wrong way. It orbits backwards relative to Neptune’s spin, and orbit is almost perpendicular to its parent planet.
Third, it looks like a cantaloupe.Covered in bumpy, wrinkly features nicknamed cantaloupe terrain.
Fourth, it's actually no mere moon, but instead a victim of an interplanetary kidnapping.
Triton is likely a Kuiper belt object, like Pluto and Eris. Long ago, it fell into the vicinity of Neptune and got captured by the planet’s gravity.
Either Triton just got unlucky and had the exact wrong orbit to land itself near Neptune, or it suffered some collision with one of Neptune's own moons and losed enough energy to remain in orbit.
Sadly, it's future isn’t bright either. Due to tidal forces Triton’s orbit is decaying, and it's slowly spiralling into its doom. It’ll either crash into Neptune or will be ripped apart into a spectacular ring system— more dazzling than Saturn's..