New dwarf planet found in our solar system, scientists say

The rock is probably one of hundreds of dwarf planets sitting on the edge of our neighbourhood

The scientists were scanning our galaxy, the Milky Way, when they spotted the all important rock (Rex)

Scientists have found another dwarf planet hiding out in our solar system.

The rock – about 330 miles wide and 8.5 billion miles from the sun – is so distant from us and its star that it takes 1,100 of our years to orbit it once.

It has been named 2014 UZ224, and is about to join the very short list of dwarf planets that exist in our own solar system. But it’s probably just one of potentially almost 1,000 of them, according to experts.

The discovery was done using a special Dark Energy Camera that was developed by students at the University of Michigan and by physicist David Gerdes. That system was developed to create a map of the galaxy – but helped spot the new planet while it was doing so.

The way that astronomers find solar system objects while taking pictures of the sky, as David Gerdes did, is looking for things that move over time. If they are, then there’s likely to be something of interest about them.

"Objects in the solar system, when you observe them at one instant and then a little while later, they appear to be in a different place in the sky," Gerdes told NPR.

Much of the things that are in the far distance of our galaxy are so far away that they tend to look as if they’re not moving at all. So anything that moves more quickly is likely to be of note, and much closer by.

That is not as easy as it seems because those objects can sometimes just be spotted once. They might be seen again another two weeks later, or many months later – and so the scientists had to create software that had to connect the dots and trace the object as it moved across the sky.

The dwarf planet joins Pluto and a small number of other ones – Ceres, Eris, Haumea and Makemake – in the list of recognised ones in our own solar system. But though the International Astronomical Union has recognised the discovery of 2014 UZ224, it won’t officially get to join the ranks of the dwarf planets until further study has been done.

A dwarf planet is defined as something that looks and behaves like a planet, but is far smaller. The definition can be loose and it is often difficult to pin down whether a rock counts as a dwarf planet or a full one – which is the reason for the long time that it took for Pluto to have its status changed, and the various people who are still annoyed about that.

Mike Brown, who became famous as the “Pluto killer” for his work on having the rock downgraded to a dwarf planet, says that there are possibly around 1000 dwarf planets lurking on the edge of the solar system.

Brown has been one of the many scientists combing through the sky for hints of Planet Nine. That is a much bigger planet that has been suggested – possibly 10 times the size of Earth – and while there’s not yet been any direct evidence there is plenty of apparent information that suggests it is out there.

Some of the same images that Gerdes used to spot the new dwarf planet could reveal Planet Nine itself, he told NPr.

"I'm excited about the chances of the people in this room finding it,” he told NPR. “Of course I'm happy for humanity if someone else finds it, it would be the most exciting astronomical discovery in our lifetime, I think."