Astronomers have discovered what is called an exomoon, estimated to be the size of Neptune in an orbit around a gigantic gas planet 8,000 light years from Earth. The moon was found outside our solar system.
Although Our solar system has nearly 200 natural satellites, interstellar ones have been quite elusive. Astronomers have had success locating exoplanets around stars outside our solar system, but exomoons are harder to pinpoint because of their smaller size.
‘This would be the first case of detecting a moon outside our solar system,’ said David Kipping, an assistant professor of astronomy at Columbia University and one of the discoverers of the potential exomoon. ‘If confirmed by follow-up Hubble observations, the finding could provide vital clues about the development of planetary systems and may cause experts to revisit theories of how moons form around planets.’
Kipping has spent a decade working on the ‘exomoon hunt.’
Despite this finding, the scientists are cautious about confirming that the new find is an exomoon due to its peculiarities and the need for more observation. Their results were published Wednesday in the journal Science Advances.
‘This is not by itself a proof of an exomoon,’ Kipping said. ‘It’s the unknown of unknowns which are ultimately uncharacterizeable.’
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However, the finding is both promising and intriguing. The moon, which orbits a giant exoplanet called Kepler-1625b, is incredibly large, comparable to the size of the gas giant Neptune in our solar system. There’s no analog for such a large moon in our own system. In our sky, it would appear two times bigger than Earth’s moon, the researchers said.
But that size is why it was easier to find, the researchers said. It’s comparable to so-called hot Jupiters, gas giant exoplanets that are closer to their stars than Jupiter is to its own, and warmer. These were common discoveries during the early days of exoplanet hunting because they were easy to find, but they represent only about 1% of known exoplanets now.
The planet that the potential exomoon orbits, Kepler-1625b have a mass similar to the size of the earth and its moon.
It was discovered when Columbia astronomers Kipping and Alex Teachey used NASA’s Hubble Space Telescope to follow up on an intriguing find from data in the Kepler Space Telescope’s exoplanet catalog. This catalog included 284 planets found by Kepler with wide orbits around their host stars. Kepler-1625b stood out.
‘We saw little deviations and wobbles in the light curve that caught our attention,’ Kipping said.
Scientist still considers the exomoon a mystery but remain excited about the possibilities. It’s not like the exomoon in ‘Avatar’ or Endor from ‘Star Wars,’ Teachey said, ‘but going forward, I think we’re opening doors to finding worlds like that.’
The researchers believe the star system to be 10 billion years old, which means it’s had time to evolve. This could explain why the moon is 3 million kilometers from its planet; they were probably closer in the past.