For decades, scientists have theorised that there is a ninth planet – what would have been the 10th were it not for the downgrade of Pluto to a dwarf planet – in our galactic neighbourhood. The planet, named Planet Nine, is believed to be five times bigger than Earth and 20 times farther out from the sun than Neptune – the outer-most planet in the solar system. While Planet Nine’s existence has yet to be officially proven, researchers strongly suspect that there is a large planet lurking in the far edge of our solar system.
There are a number of odd features in our solar system that would be explained by Planet Nine.
One is that the Kuiper Belt – a circumstellar disc full of icy asteroids, comets and dwarf planets which encompasses the solar system – orbits in the opposite direction to the planets within it.
While there is no solid evidence of the monster planet lurking on the edge, a new study has claimed that NASA has likely already seen the planet – but the space agency does not know yet.
This is because of NASA’s Transiting Exoplanet Survey Satellite (TESS) – which looks for planets outside the solar system.
TESS takes thousands of images of deep space as it circles Earth and the chances are it has already observed Planet Nine.
However, the elusive planet may not have shown up as TESS looks for planets by analysing the transit zone of a distant star.
The transit zone is the region in which a planet crosses a star relative to TESS, casting a tiny shadow which the satellite can detect.
However, if Planet Nine is out there, it would not have a transit zone relative to TESS because it is so far away from its host star – our sun.
“The main thing I don’t think people realised before is if you have a small telescope like TESS, you can combine images and find faint objects.”
TESS has already looked at the entire southern hemisphere, so if Planet Nine is in that region, there is “practically 100 percent” chance that NASA has observed it, according to Mr Holman.
He added: “If it’s in the Northern Hemisphere, we’re not there just yet.”