Exomoons: astronomers report first ever discovery

Pablo Tucker
October 6, 2018

Analysing data from the Kepler and Hubble space telescopes, the researchers believe the so-called "exomoon" is the size of Neptune, and orbits a planet the size of Jupiter.

According to the recent study, the object orbiting Kepler-1625b might indeed be an exomoon as the giant planet passed before its host star one hour before the astronomers predicted.

Astronomers David Kipping, from Columbia University in NY and Alex Teachey are reporting and publishing the results Science Advances journal observing all the hypothesis and anomalies, comparing the data they have other planets in the system or stellar activity but they still can not explain the new discovery. Kipping and Tichy noticed a unusual anomaly in the data concerning the transit of the gas giant Kepler 1625b, which is several times more than Jupiter. And excitingly, some of the moons around the giant planets in our solar system - including Europa, Enceladus and Titan - are now our best bet for finding life outside our own planet (or possibly on Mars).

Kipping and co-author Alex Teachey, a student at Columbia, published the results of their discovery on Wednesday.

The exomoon and its planet orbit Kepler-1625, a star similar in temperature to our sun but about 70 percent larger.

To find an exoplanet, astronomers rely on spotting the tiniest dips of light as a planet passes in front of its host star (the transit method) - which themselves are only small pinpricks of light when viewed with even the largest telescopes.

The researchers requested time on the Hubble Space Telescope, and their request, which was public, generated a bit of excitement among those who follow new planet discoveries. This phenomenon astronomers call a "transit".

That planet, called Kepler-1625b, is one of thousands that scientists have recently detected around distant stars.

This decrease in dimness is consistent with "a moon trailing the planet like a dog following its owner on a leash", Kipping said. "But we knew our job was to keep a level head testing every conceivable way in which the data could be tricking us until we were left with no other explanation".

Astronomers were looking for a uniform brightness change of the planet, indicating the presence of the satellite, and also observed gravitational effects.

"Both bodies, however, are considered to be gaseous and therefore unsuitable for life as we know it", Kipping said.

"We hope to re-observe the star again in the future to verify or reject the exomoon hypothesis", Kipping tells Wall as Space.com.

In an attempt to confirm their original tentative detection, the team behind the new study scheduled high precision measurements of Kepler-1625 with the Hubble Space Telescope, which were carried out in October 2017.

Accepting that the data do indeed show evidence for an additional body co-orbiting the star with the planet Kepler-1425b, the question arises - is this really a moon?

Moons are kind of the next frontier when it comes to understanding alien solar systems, says Bedell: "They capture our imagination".

"But moving forward, I think we open the door to search for such worlds", said Teachey.

GREENFIELDBOYCE: The researchers have requested more time on Hubble to do more observations next May.

"This would be the first case of detecting a moon outside our solar system".

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