For years, astronomers have teased the concept of another world in our solar system, commonly referred to as Planet Nine.
But there could be a whole other ‘Earth-like’ planet waiting to be discovered much closer to home, Japanese astronomers now reveal.
They think this new planet is hiding in the Kuiper Belt, the doughnut-shaped ring of objects extends just beyond the orbit of Neptune.
This so-called Kuiper Belt planet (KBP) is up to 500 astronomical units (AU) from the sun – 500 times the distance between Earth and the sun, and closer than Planet Nine.
KBP is up to three times as massive as Earth, the experts say, but temperatures are likely too cold to sustain life as we know it.
Astronomers in Japan believe an Earth-like world could be hiding within our solar system, waiting to be discovered (file photo)
READ MORE Does Planet X really exist?
If Planet Nine exists, its hypothetical orbit would see it take between 10,000 and 20,000 years to go around the sun
<!—->
Advertisement
The study was conducted by Patryk Sofia Lykawka of Kindai University in Osaka, Japan and Takashi Ito of the National Astronomical Observatory of Japan in Tokyo.
‘We predict the existence of an Earth-like planet,’ they say in their paper, published in The Astronomical Journal.
‘It is plausible that a primordial planetary body could survive in the distant Kuiper Belt as a KBP, as many such bodies existed in the early solar system.’
It’s known that the Kuiper Belt contains millions of icy objects, referred to as trans-Neptunian objects (TNOs) because they’re beyond Neptune.
TNOs are thought to be what’s left over from the formation of the solar system and composed of mixtures of rock, amorphous carbon and volatile ices such as water and methane.
‘The orbits of trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system,’ the Japanese team say.
‘These rock and ice bodies are the remnants of planet formation in the outer solar system.’
NASA describes the Kuiper belt as a ‘region of leftovers from the solar system’s early history’. The experts think the Earth-like planet resides in the belt, closer to the sun than the hypothesised location of Planet Nine
An Earth-like planet can explain three fundamental properties of the distant Kuiper Belt, including a ‘significant population of high-inclination objects’ (pictured)
The team noticed that some of these objects have ‘peculiar orbits’ that suggest they are being gravitationally influenced by something larger close by.
The belt also has a significant population of high-inclination objects – those with a high tilt as they orbit around the sun.
Computer simulations suggested the hypothetical KBP could be responsible for these effects.
‘We determined that an Earth-like planet located on a distant and inclined orbit can explain three fundamental properties of the distant Kuiper Belt,’ they write.
‘[These are] a prominent population of TNOs with orbits beyond Neptune’s gravitational influence, a significant population of high-inclination objects, and the existence of some extreme objects with peculiar orbits.’
The experts note that they are predicting rather than confirming the Kuiper Belt planet exists, as more research will be required.
They also stress that their proposed planet is different from the already-hypothesized Planet Nine, which is much more massive and thought to be located on a more distant orbit.
Planet Nine was first theorised by experts from Caltech in 2014 when, similarly, they spotted that the orbits of the most distant TNOs were being perturbed or disrupted.
Astronomers still claim that this can be explained by the gravitational pull of a ninth planet in our solar system that orbits 20 times farther from our sun than Neptune.
However, to date, astronomers have only circumstantial evidence for the existence of Planet Nine – and some aren’t convinced it exists at all.
If it exists, Planet Nine is in the outer reaches of our own solar system, beyond the Kuiper Belt, rather than within it.
Planet Nine could have formed in the inner solar system at its genesis and was then kicked out by interactions with Jupiter, another team of researchers said in 2020.
Another study published earlier this year suggested Planet Nine could be surrounded by 20 hot moons, which might help experts find it.
PLANET NINE: ORBITS OF OBJECTS BEYOND NEPTUNE SUGGEST ‘SOMETHING LARGE’ IS THERE
Astronomers believe that the orbits of a number of bodies in the distant reaches of the solar system have been disrupted by the pull of an as yet unidentified planet.
First proposed by a group at CalTech in the US, this alien world was theorised to explain the distorted paths seen in distant icy bodies.
In order to fit in with the data they have, this alien world – popularly called Planet Nine – would need to be roughly four times the size of Earth and ten times the mass.
Researchers say a body of this size and mass would explain the clustered paths of a number of icy minor planets beyond Neptune.
First proposed by a group at CalTech in the US, this alien world was theorised to explain the distorted paths seen in distant icy bodies.
Its huge orbit would mean it takes between 10,000 and 20,000 years to make a single pass around the sun.
The theoretical Planet Nine is based on the gravitational pull it exerts on these bodies, with astronomers confident it will be found in the coming years.
Those hoping for theoretical Earth-sized planets proposed by astrologers or science fiction writers – which are ‘hiding behind the sun’ and linked with Doomsday scenarios – may have to keep searching.
