There is probably no “Planet Nine” on the edge of the solar system, astronomers say, after a study found unusual orbits used to predict its existence “could be an illusion.”
Experts at the University of Michigan have looked at the results of a number of solar system surveys to look for evidence of the long-theorized “super Earth” -like planet.
The Planet Nine theory gained traction in 2016 after astronomers at the California Institute of Technology linked a strange cluster of objects in and beyond Neptune’s orbit with a large planet on the edge of the solar system.
This planet, nicknamed Planet Nine, is said to be up to ten times larger than Earth and up to 400 AU from the Sun – that is, 400 times farther from the Sun than Earth – but no evidence of its existence. was not found. .
Looking at the results of three different studies of these very distant extreme transneptunian objects (ENTOs), the team found no evidence of an actual clustering, suggesting it was simply ‘selection bias’. due to the small number of ENTOs found.
There is probably no ‘Planet Nine’ on the edge of the solar system, say astronomers, after study found unusual orbits used to predict its existence ‘could be an illusion’
Astronomers Konstantin Batygin and Michael Brown of Caltech first proposed the idea of Planet Nine changing the orbits of ENTOs in 2016.
These distant objects have huge elliptical orbits and never come any closer to the Sun than Neptune’s orbit at 30 AU but can go up to 150 AU.
An AU, or astronomical unit, is the distance between the sun and Earth or approximately 149 million km – so Neptune at 30 AU is 4.4 billion km from the sun.
As these ENTOs are so far from the sun that they can be very difficult to spot, so surveys tend to focus and select potential targets, which creates possible selection bias.
Looking at the results of three different studies of these very distant extreme transneptunian objects (ENTOs), the team found no evidence of an actual clustering, suggesting it was simply ‘selection bias’. due to the small number of ENTOs found.
The Planet Nine theory gained traction in 2016 after astronomers at the California Institute of Technology linked a bizarre cluster of objects in and beyond Neptune’s orbit with a large planet on the edge of the solar system
In their 2016 study, Batygin and Brown found that the ETNOs they discovered had the same angle at perihelion – the point where they are closest to the sun.
This is an unusual amount of clustering and so they created a simulation suggesting that a large super-terrestrial planet could cause ETNOs to cluster this way.
However, ETNOs are extremely difficult to find as they are relatively small and very far out in a very large night sky with plenty of room to study.
This means that we can only really see them when they are at or near perihelion – when they are relatively close to the Sun – because they are impossible to find after that point.
Very few were actually found, with Brown and Batygin’s simulation based on just six – and in circumstances where the selection bias was unclear.
Since 2016, a number of other surveys have found more of these distant objects, and by combining them for this new study, Michigan researchers were able to determine that selection bias played a large role in the theory of clustering.
They found no evidence of a clustering among ETNOs, which rejects the idea that a large object could be the cause as it does not exist.
They took objects from the investigation into the origin of the outer solar system – which found no evidence of clustering, objects from the dark energy investigation and the work of astronomers leading the search for planet nine.
Each of those surveys had a different goal in mind and a different selection bias – so the Michigan team, led by physicist Kevin Napier, had to take that into account.
Mike Brown (left) and Assistant Professor Konstanin Batygin came up with the idea that extreme transneptunian objects clustered together due to a large planet on the edge of the solar system
They created a “survey simulator” that simulates detections based on a body population model of the solar system – using previous surveys and criteria as a basis.
This allowed the team to account for any bias in previous surveys and create a picture of the true underlying populations of ETNO.
If a physical object such as a large planet caused clustering, it should have remained consistent across the larger sample set created by Napier and his colleagues – mirroring the results of the original team’s simulation of six objects. .
The results do not match up, however, suggesting instead that ETNOs in the solar system follow a uniform distribution, as one would expect – no strange clustering.
Michigan team member David Gerdes wrote on Twitter that when searching for ETNO you “find them where you look” and that previous surveys had not looked for enough places to claim that ‘they had a cluster orbit.
Napier did not rule out the possibility that a ninth major planet exists in the solar system, simply that its existence cannot be deduced from ETNO data alone.
He said there was not enough information to confirm or rule out its existence, as other evidence, including the strange orbits of outer solar system objects such as Sedna in the Kuiper Belt, could suggest a large planet.
When the Vera Rubin Observatory goes live later this year, it will be able to collect much more data on ETNOs and create a more complete picture of their population.
The results of the new study have been published on the arXiv.org pre-printing site.
PLANET NINE: OBJECT ORBITS BEYOND NEPTUNE SUGGESTED THERE’S SOMETHING BIG
Astronomers believe that the orbits of a number of bodies in remote regions of the solar system have been disrupted by the pull of an as yet unidentified planet.
First proposed by a CalTech group in the United States, this alien world was theorized to explain the distorted paths observed in distant frozen bodies.
In order to accommodate the data they have, this alien world – commonly known as Planet Nine – would need to be about four times the size of Earth and ten times its mass.
Researchers say that 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 CalTech group in the United States, this alien world was theorized to explain the distorted paths observed in distant frozen bodies.
Its huge orbit would mean that it would take 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, and astronomers are confident that it will be found in the years to come.
Those hoping for theoretical Earth-sized planets proposed by astrologers or science fiction writers – which are “hiding behind the sun” and tied to doomsday scenarios – may need to keep looking.
