Astronomers may have located first exomoon
There are about 200 moons in our own solar system, including Earth’s aptly named “moon.” Astronomers may have discovered the first “exomoon” – a moon outside the solar system.
This potential new moon orbits a giant, Jupiter-size planet about 8,000 light-years from Earth.
“This would be the first case of detecting a moon outside our solar system,” said David Kipping, an astronomer at Columbia University and lead author of a study about the finding.
It is not only the planet that’s huge. This new moon – if that’s what it is – is gigantic, about the size of Neptune.
Astronomers used data and observations from the Kepler and Hubble space telescopes to study the distant star, planet and possible moon.
Although the object itself cannot be seen, there are hints it exists, according to the researchers: The planet moves around its star in a way that indicates something else is pulling on it gravitationally, probably a moon.
As the planet moved in front of the star, the star’s light dimmed too much. There was something else in the way.
This decrease in dimness is consistent with “a moon trailing the planet like a dog following its owner on a leash,” Kipping said.
A moon “is an excellent explanation” for these observations, he said.
Study co-author Alex Teachey, also of Columbia, urged caution: “The first exomoon is obviously an extraordinary claim, and it requires extraordinary evidence.
“Furthermore, the size we’ve calculated for this moon, about the size of Neptune, has hardly been anticipated, and so that, too, is reason to be careful here,” Teachey said.
Only two planets in our solar system – Mercury and Venus – don’t have moons, Kipping said.
He said, “We hope to re-observe the star again in the future to verify or reject the exomoon hypothesis.” The research team hopes to take another look at the star next May, if there is time available on the Hubble.
“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 said.