By studying data from NASA’s Cassini spacecraft orbiting Saturn, the seventh planet from the Sun, they could exclude two zones, the team wrote in the journal Astronomy and Astrophysics.
Their work confirmed that a ninth planet might exist in the far reaches of our Solar System, co-author Jacques Laskar of the Paris Observatory said, “but not just anywhere”.
Based on mathematical modelling, the French scientists calculated what influence a ninth planet — travelling along the orbit speculated by the American scientists — would have on the movement of other planets as it passed nearby.
They then looked at how the known planets actually behaved.
The planet is thought to circle the Sun in a lopsided, highly elongated, oval loop.
At its most distant from the Sun, the planet would be too far too away for any effect on other planets to ever be detectable, thus limiting astronomers to a searchable zone representing only about half of the total orbit.
Now Mr Laskar and his team have reduced the search area by 50 per cent by eliminating two zones in which they say the modelling does not match reality.
“We have cut the work in half,” he told the AFP news agency.
Its existence was predicted with mathematical modelling and computer simulations, and was said to exactly explain the strange clumping behaviour of a group of dwarf planets in the Kuiper Belt, a field of icy objects and debris beyond Neptune.
Mr Laskar and his team said the search field could be further narrowed if Cassini, due to finish its mission next year, was extended to 2020.
Astronomers expect it would take years to find Planet Nine, if it exists at all. It would take a very large telescope to spot the planet at that distance, and with no clear idea of where on its very large orbit it is.
Many other planets have been predicted through modelling over the years, mostly wrongly.
In one famous case the science was right — the discovery of Neptune, first predicted from its gravitational pull on Uranus.
news.com.au 25 Feb 2016
Isn't Planet Nine/Nibiru/X supposed to be a 'conspiracy theory'?