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There’s a new dwarf planet in our solar system, and it’s the most distant one we’ve ever discovered. The tiny world, formally known as 2018 VG18 but nicknamed Farout, is about 18 billion kilometres away – roughly 3.5 times the distance to Pluto.

A team of astronomers discovered Farout using the Japanese Subaru telescope in Hawaii. Solar system objects like this are found by looking at a series of images of the same spot of sky for any dot that appears to be moving in comparison to the background stars.

“I said ‘far out!’ when I discovered it, and it’s a very far out object,” says team member Scott Sheppard at the Carnegie Institution for Science in Washington DC.

We don’t know much about Farout yet because of its extreme distance. The images showed that it is about 500 kilometres across, big enough for it to be a dwarf planet. It also appears to be a pinkish colour, which might indicate that it has an icy surface.

More observations of this tiny world should help us pin down an important detail: its orbit. The strange orbits of similar distant objects have led astronomers to hypothesise that they might be pushed around by a huge planet on the outer edges of our solar system. This as-yet unseen object has been dubbed Planet X.

If Farout’s orbit is similarly warped, it might help us narrow down our search for the elusive planet. In fact, the astronomers found Farout while searching the sky for Planet X.

“It could further show that there is a planet out there, but that has to wait until we know the orbit,” says Sheppard. “But the orbit is likely over 1000 years long, so it’s going to take several years of observations to really determine what it is.”