Scientists have discovered a tiny mysterious planet in a strange orbit beyond Neptune on the outer edge of the solar system.

Nicknamed Niku, it appears to be a trans-Neptunian object and it has got scientists baffled.

RT reports:

Niku, named after Chinese word for ‘Rebel’, has a diameter of just 200km (120 miles), is 160,000-times smaller than Neptune and behaves like no other similarly-sized planet in the Solar System.