The Alien Observatory –“Strange, Saturn-Sized Alien Moon May Be a Harbinger of Habitable Worlds”

 

Exomoons

 

"The first exomoons that we find will be large – maybe Mars- or even Earth-sized – and therefore intrinsically more likely to be habitable than small moons," said René Heller, at the Leibniz Institute for Astrophysics in Potsdam, Germany. "With Kepler finding many more giant planets than terrestrial planets in stellar habitable zones, it's really important that we try to figure out what conditions might be like on the moons of these giants to gauge if they can host extraterrestrial life."

 


In a series of papers published in 2013, Heller and his colleague Rory Barnes from the University of Washington and the NASA Astrobiology Institute tackled some of the big-picture problems to habitability posed by the relationship between exomoons and their host planets. Heller and Barnes have proposed a circumplanetary "habitable edge," similar to the well-established circumstellar "habitable zone." This zone is the temperature band around a star within which water neither boils off or freezes away on a planet's surface – not too hot, not too cold, thus earning it the nickname "the Goldilocks zone.

 

This past July, 2017 reports New Scientist, evidence emerged of the first discovery of a moon around a planet beyond our solar system that might prove Heller's 2013 prediction above correct. Although the exomoon’s existence has yet to be confirmed, new results from Kepler Data 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 sifting through data from the Kepler space telescope on more than a thousand planets and their moons orbiting distant stars. Back in July, he and his graduate student Alex Teachey announced they had found signs of the colossal exomoon that might orbit a gas giant roughly 4000 light years away. A moon, says Kipping, could also make its host planet more likely to harbor life. Some models suggest that the presence of our moon might have helped make Earth a nice place to live. The same could be true for other moon-planet partnerships.

So Kipping’s search, dubbed the "Hunt for Exomoons with Kepler," gets at the fundamental nature of our place in the universe: Are we alone? By early next spring, astronomer David Kipping hopes to know if the object he’s spent his early career searching for is really there.

In late October, 2017, Kipping and colleagues will use the Hubble Space Telescope to find out if they’ve caught their first quarry. The possible candidate is a Neptune-sized object orbiting the planet Kepler 1625b. If the candidate turns out to be a genuine exomoon (Kipping is quick to point out that similar hints have fizzled before) he will no doubt solidify his reputation as “the moon guy.”

“His signature projects are quite risky, but with obvious large payback,” says Dimitar Sasselov, director of the Harvard Origins of Life Initiative, who worked with Kipping in his postdoc research at Harvard University.

There’s a reason Kipping’s team has found only one exomoon candidate so far: There aren’t many out there big enough for Kepler to see, according to his statistical work. “Because he’s doing such a careful job, it probably means something,” Sasselov adds. The systems the team has checked that show no moons most likely aren’t hiding any.

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.

Heller, still at the Max Planck Institute for Solar System Research in Germany, speculates that based on calculations from the Kepler data, 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 most likely scenario, is a Neptune-like world larger than any moon that exists in our solar system, which means that its formation mechanism would be A mysterY.

Heller argues that it's size can’t be explained by what we currently know about how moons form in our solar system, where Earth's moon was created when a giant impact carved the satellite from our planet, and Jupiter’s moons formed around the developing planet from the thick debris of gas and dust that once persisted throughout the solar system. Neptune’s moon was actually captured by the planet’s gravity.

If Kipping's exomoon is validated, it would pose “an exquisite riddle for formation theorists to solve”, Heller says. “It is not clear to me from the Kepler data and from what we know in the solar system, which channel it would have formed through.”

“If it’s there, awesome, have at it,” Teachey says. “But if not, well, we’d feel badly about other people having spent time studying a phantom.”

“I think the conclusion is, ‘this is a strange system,’ and we agree,” Teachey says. Both he and Kipping have argued that the unusual size of the moon is reason to be agnostic about it, but that doesn’t necessarily mean astronomers should rule out its existence. “The universe is very good at surprising us,” Teachey says.

The Daily Galaxy via Daily GalaxyNew Scientist,  Science News , ARXIV

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