Page 38 - All About Space 68 - 2017 UK

Search for Planet Nine

t the very edge of our Solar System, For this kind of clustering of these objects, there Nine may be hiding in a set of data somewhere. “It’s
twenty times further away than Neptune, is around a 0.007 (or one in 15,000) chance it is possible it's sitting in an already existing dataset, but
and 700 times the distance from Earth to being caused by a coincidence. Brown and Batygin’s has not been correctly interpreted,” Batygin says.
A the Sun, there lies a mystery. A planet, ten reasoning was if a planet large enough was orbiting “Indeed, one approach to look for Planet Nine would
times more massive than our own, could be lurking. beyond the Kuiper Belt, its gravity could be the force be to scan already existing data. We’ve done this to
Now, as evidence is being gathered, we may have behind the mystery. They described Planet Nine as an extent, but we are far from complete.”
already discovered this world without realising it yet. the last resort after all other possible explanations for Results published last month from the Outer
Once upon a time there were nine planets in our the clustering were exhausted. Solar System Origins Survey (OSSOS), a four-year
Solar System. In 2003, an astronomer called Mike A few months after the paper was published, telescope survey that ended recently, seemed to dash
Brown discovered a dwarf planet called Eris, which using data from the Cassini spacecraft, a pair of Planet Nine’s hopes. OSSOS discovered more than
is larger than Pluto, leading to Pluto being stripped astronomers worked out the possibility of several 800 objects beyond the orbit of Neptune, meaning
of its planetary status. Over ten years later, the orbits for the mystery world. They used small it could have been an opportunity to spot evidence
same astronomer that led to the demotion of Pluto fluctuations in the orbit of Cassini around Saturn, and for the orbital clustering of these objects, caused
started the journey towards our Solar System gaining found they could be better explained if a huge planet by Planet Nine. However, Cory Shankman of the
another ninth member. existed somewhere beyond the Kuiper Belt. In the University of Victoria in Canada, and his colleagues
In January 2016, a pair of astronomers from the following months, the evidence continued to mount. involved with the project, claimed to have found no
California Institute of Technology, Mike Brown and In July last year, Batygin, Brown and Elizabeth such evidence.
Konstantin Batygin, published a paper predicting the Bailey revealed Planet Nine would also explain the “Their work has received a lot of media attention
existence of a ninth planet. Their paper set to answer six-degree tilt of the Sun with respect to the plane of and you may have heard statements as strong as ‘the
a mystery of our Solar System – why six objects the inner planets; a mystery which has been puzzling Planet Nine theory is dead’,” says Raul de la Fuente
far beyond Neptune, in an icy region known as the us for over 150 years. Marcos, a researcher based in Spain who is also
Kuiper Belt, were tilted and orbiting in one particular Since then, astronomers around the world focused looking into planets beyond Pluto. But this is not the
direction. These objects are known as extreme their attention on proving, or disproving, the case. While the paper could be seen as casting doubt
trans-Neptunian objects (ETNOs), and their strange existence of this hypothetical world. Now, enough on the existence of Planet Nine, Batygin remains
behaviour has started a distant space investigation. data has been collected that Batygin thinks Planet optimistic. He says the survey only looked at a small

“ We still believe that there are two or more

planets beyond Pluto” Raul de la Fuente Marcos

© Tim Abott, CTIO/NOAO

The Victor M. Blanco telescope at Cerro Tololo Interamerican
Observatory (CTIO) in Chile collects images using its
570-megapixel camera to search for Planet Nine

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