In July, tantalising evidence emerged of the first discovery of a moon around a planet beyond our solar system. Although the exomoon’s existence has yet to be confirmed, new results show that the world may look stranger than anyone thought and may also have been created through some unknown mechanism.
David Kipping at Columbia University, New York, has spearheaded an effort to comb through Kepler spacecraft data in search of hidden moons since 2012. Back in July, he and his graduate student Alex Teachey announced they had found signs of a colossal exomoon that might orbit a gas giant roughly 4000 light years away.
Although the moon is still hypothetical – and Kipping has watched many previous candidates vanish into thin air – the discovery would mark a new chapter in our search for life in the cosmos, causing many to wonder what that world would look like.
René Heller at the Max Planck Institute for Solar System Research in Germany set out to determine just that.
Not that it is an easy question. Given that the exomoon has yet to be confirmed, very little is known about it so far – so its exact size and mass are unknown. Based on calculations from the Kepler data, Heller speculates that the moon could be anything from a small gaseous body the size of Earth to an ocean-covered rocky world as big as Saturn. But he thinks the most likely scenario, sitting squarely in the middle of that range, is a Neptune-like world.
Such a mega-moon doesn’t exist in our solar system, which would make this candidate exomoon an oddball. It also means that its formation mechanism might be quite mysterious.
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