A group of French scientists have said they are closer to pinning down the location of Planet Nine, the mystery potential new addition to the list of major satellites orbiting the Sun.
US astronomers announced in January that theymay have found a ninth planet beyond Neptunebut said it could take 10,000 to 20,000 years to orbit the Sun and they had no idea where it might be.
By studying data from Nasa’s Cassini spacecraft orbiting Saturn, the seventh planet from the Sun, the French scientists excluded two zones, they 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 told AFP, “but not just anywhere”.
Based on mathematical modelling the French scientists calculated what influence a ninth planet – travelling along the orbit postulated by the Americans – would have on the movement of other planets as it passed nearby.
They then looked at how the known planets actually behaved.
The postulated 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 be detectable, thus limiting astronomers to a searchable zone representing only about half of the total orbit.
Now Laskar and his team have reduced the search area by 50% by eliminating two zones in which they say the modelling does not match reality.
“We have cut the work in half,” he told AFP.
Last month astronomers Konstantin Batygin and Mike Brown predicted the existence of what they dubbed Planet Nine, about 10 times more massive than Earth.
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.
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.(Agence France-Presse)
Link: https://www.theguardian.com/science/2016/feb/24/search-narrows-for-planet-nine-along-sprawling-orbit-of-thousands-of-years
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