Astronomers have time and again discovered a lot of exoplanets or the planets that are located outside our solar system and orbit suns. However, ever since the discovery of exoplanets, scientists have been hunting on for exomoons. And now, they may have found the very first moon outside our solar system or the first alien moon, thanks to NASA’s Kepler telescope.
The new discovery may help scientists to understand more about how the planets, moon and stars formed. Astronomers have said that a huge moon the size of Neptune orbits a planet located around 4,000 light-years away, however they have made it clear that they are yet to confirm its existence.
If the presence of this alien moon is confirmed, it would be a major breakthrough in astronomers’ study of the cosmos. The massive moon would be the first discovered in orbit around an alien world.
Detecting a moon outside the solar system as a big achievement, however, its existence needs to be verified. In October 2017, the scientists will train the Hubble Space Telescope on the home star of the planet to check if the signal holds up.
“This candidate is intriguing, and we obviously feel good enough about it that we've asked for Hubble time,” coauthor Alex Teachey, a graduate student at Columbia University, says in an email. “But we want to be crystal clear that we are not claiming a detection at this point.”
Yet another achievement for NASA’s Kepler telescope?
If scientists confirm the existence of the alien moon, this would add yet another feather in the cap for NASA’s Kepler telescope. The Kepler was launched in 2009 and since then it has discovered more than 2,000 alien worlds and about 4,000 candidate planets. Scientists using Kepler data identified 219 more candidates alien planets in June. The planets include those that may be habitable like our Earth.
From the point of view of Earth, Kepler detects when these planets pass in front of their home stars. During the transit, a fraction of the star’s light gets blocked, resulting in a periodic dip in apparent brightness.
It is a daunting task to detect a moon orbiting a planet using this same technique. The transits of moons don’t block much starlight because they are smaller than their planets. Astronomers must painstakingly tease apart the signals from moon and the planet it’s orbiting.
However, scientists remain unperturbed from trying to find alien moons, some of which might be habitable.
Columbia University astronomer and study coauthor David Kipping has spearheaded the Hunt for Exomoons with Kepler (HEK) since 2012, in an effort to comb through Kepler data for hints of moons.
The new paper of the researchers has been published on the preprint service arXiv. It focusses on 284 Kepler planets that are the likeliest to have moon systems resembling Jupiter’s. The transit data of these planets was then statistically stacked as the team hoped to see smears that moons would leave in the collective signal.
Some of the planets are as big as the size of the Jupiter and nestled close to their stars. These are formed in the chillier outskirts of their star systems then migrated inward, astronomers believe. This raised questions about what would happen to their moons.
“They’re looking at planets that are much closer to their suns than Jupiter is to our own,” says Leiden Observatory astronomer Matthew Kenworthy, who wasn’t involved with the study. “So the question is, during this process of migration, do big fat gas giants lose their moons?”
These Kepler planets are not teeming with moons, the latest data suggests. 108 of the 284 studied worlds could have them, said researchers, suggesting that many Jupiter-like planets do shed their moons if they migrate.
Will existence of moon beyond solar system be proved?
When quick-and-dirty moon models were applied to 284 individual planets, a compelling signal from Kepler-1625b was uncovered. A smaller, Neptune-size body was orbiting the planet, additional bumps in the data suggested.
The Hubble observations scheduled for October will break or make the case for the moon. “If it’s true, it’d be awesome,” says Kenworthy. “But right now, and [the study authors] say this very clearly, it’s tantalizing. It’s not a detection.”
“Any time the word ‘candidate’ is in the [study] title, it is just that, a candidate,” MIT planetary scientist Sara Seager says in an email. “I am definitely looking forward to the Hubble Space Telescope observations in 2017 to see if anything is actually there.”