ANU is launching a search for a new planet in our Solar System, inviting anyone around the world with access to the Internet to help make the historic discovery.

Anyone who helps find the so-called Planet 9 will work with ANU astronomers to validate the discovery through the International Astronomical Union.

ANU astrophysicist Dr Brad Tucker is leading the project, which is being launched by Professor Brian Cox during a BBC Stargazing Live broadcast from the ANU Siding Spring Observatory.

"We have the potential to find a new planet in our Solar System that no human has ever seen in our two-million-year history," said Dr Tucker from the ANU Research School of Astronomy and Astrophysics.

Dr Tucker said astronomers had long discussed the likelihood of a ninth planet on the outer edges of the Solar System, but nothing had been found yet.

"Planet 9 is predicted to be a super Earth, about 10 times the mass and up to four times the size of our planet. It's going to be cold and far away, and about 800 times the distance between Earth and the sun. It's pretty mysterious," he said.

The ANU project will allow citizen scientists to use a website to search hundreds of thousands of images taken by the ANU SkyMapper telescope at Siding Spring.

SkyMapper will take 36 images of each part of the southern sky, which is relatively unexplored, and identify changes occurring within the Universe.

Finding Planet 9 involves citizen volunteers scanning the SkyMapper images online to look for differences, Dr Tucker said.

"It's actually not that complicated to find Planet 9. It really is spot the difference. Then you just click on the image, mark what is different and we'll take care of the rest," Dr Tucker said.

He said he expected people to also find and identify other mystery objects in space, including asteroids, comets and dwarf planets like Pluto.

"If you find an asteroid or dwarf planet, you can't actually name it after yourself," Dr Tucker said.

"But you could name it after your wife, brother or sister. We need to follow all of the rules set by the International Astronomical Union."

Dr Tucker said modern computers could not match the passion of millions of people.

"It will be through all our dedication that we can find Planet 9 and other things that move in space," he said.

Co-researcher and Head of SkyMapper Dr Chris Wolf said SkyMapper was the only telescope in the world that maps the whole southern sky.

"Whatever is hiding there that you can't see from the north, we will find it," Dr Wolf said.

From 28 to 30 March at 8pm London time, BBC Stargazing Live hosted by Professor Cox and comedian Dara O Briain is expected to be viewed by around five million people.

The ABC will broadcast an Australian Stargazing Live program from Siding Spring from 4 to 6 April, hosted by Professor Cox and Julia Zemiro.

SkyMapper is a 1.3-metre telescope that is creating a full record of the southern sky for Australian astronomers.

People will be able to participate in the ANU citizen science project to search for Planet 9 at the zooniverse website. 

More details to come.

Follow the astronomers and presenters as they explore the Universe live from Siding Spring Observatory via our live blog page. We'll take you on an exclusive behind the scenes look at all the action. Join in the conversation using the @scienceANU twitter handle.