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Astronomers use new technique to search for Planet Nine

Debate continues about the possible existence of Planet Nine, a hypothesized planet that orbits the sun far beyond Pluto. Now, a pair of astronomers from Yale have tested a new technique for collecting up small amounts of scattered light from multiple sources in order to detect the potential planet.

Planet Nine would be extremely hard to spot as it is so far from the sun, with calculations putting it at between 12 and 23 times the distance from the sun as Pluto. That means it would receive very little light, which would make it very hard to spot. The new method of combining scattered light from thousands of different telescope images allows the detection of dim objects that haven’t been spotted before.

“You really can’t see them without using this kind of method. If Planet Nine is out there, it’s going to be incredibly dim,” said lead author Malena Rice, astronomer at Yale.

This deep region of the solar system is a mystery in many ways, as we have only a small amount of information about what is out there. “This is a region of space that is almost entirely unexplored,” co-author Gregory Laughlin said.

Artist rendition of “Planet Nine” looking towards the Sun Caltech/R. Hurt (IPAC)

The method is called shifting and stacking, and it involves taking a series of images from space telescopes along paths where bodies might be orbiting. By looking at a set of images, researchers can combine very faint traces of light to identify objects which had been invisible before. The pair tested out this method by using it to detect three known trans-Neptunian objects, or objects orbiting beyond Neptune.

With the method tested and reach for use, the pair then used it to search for previously unknown objects which could include Planet Nine. In total, they found 17 potential objects beyond the orbit of Neptune.

“If even one of these candidate objects is real, it would help us to understand the dynamics of the outer solar system and the likely properties of Planet Nine,” Rice said. “It’s compelling new information.”

The new information isn’t proof that Planet Nine is there, but it gives an indication of how we could search for something so distant. Rice says she is still agnostic about whether the planet exists or not, “But it would be beautiful if it’s out there,” she said.

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