Tuesday, 26 January 2016

Ninth planet theory gains momentum

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An artist’s impression of a Kuiper Belt object An artist’s impression of a Kuiper Belt object Image: Hubble ESA
  • Possible ninth planet roughly 10 times Earth’s mass
  • Planet may be hiding among solar system’s creation offcuts
  • Astronomy search began based on similar orbit anomaly

WHEN Pluto was demoted from planetary status to that of a dwarf planet, a lot of people were very upset and vocal, but now evidence is growing in favour of a new outlying ninth planet in our solar system.

The prospect of a new ninth planet is the fruition of years of work by Caltech astronomers Professor Mike Brown and Assistant Professor Konstantin Batygin who set out to show why some of the very distant objects in the Kuiper Belt orbited so similarly.

The Kuiper Belt is an area beyond Neptune’s orbit filled with billions of icy objects of various sizes that were ejected from the solar system during its creation 4.5 billion years ago.

It had been suggested that a new planet out there might have caused the orbiting anomaly, but until they created computer simulations and determined that a planet fit the bill, neither of them believed it was possible.

“Although we were initially quite sceptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we became increasingly convinced that it is out there,” A/Prof Batygin says.

The initial investigation surrounded several of these objects with very different orbits but with the inner points of their orbits all at more or less the same point in space, they felt it was a bit too close for coincidence.

They decided that a large planet, roughly ten times Earth's mass, with a long and distant orbit, could explain the anomaly they were detecting.

However, as the scenario began to take shape, the theory was strengthened when their ninth planet simulations also accounted for strange orbital properties for other distant objects in the Kuiper Belt.

“A sign of a reasonably good scientific theory is not only does it fix the problem you were trying to solve, but it also fixes a couple of other problems you hadn’t even thought about,” Curtin University astrophysicist Dr John Morgan says.

At this stage it is still just a theory and, as far as we know, we have yet to sight the new planet, Dr Morgan says.

“Over the next year or so, a lot of telescope time will be used in looking for this planet, and we’ll just have to wait and see if this theory is the correct one or whether some other theory also fits the facts,” Dr Morgan says.

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