Over 121 Known Exoplanets Could Have Earth-Like Moons That Can Support Life

Thursday, 31 May 2018 - 8:27PM
Space
Moon
Thursday, 31 May 2018 - 8:27PM
Over 121 Known Exoplanets Could Have Earth-Like Moons That Can Support Life
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NASA GSFC: Jay Friedlander and Britt Griswold
Both Jupiter and Saturn have lots of moons, and some of them like Europa could possibly support life. But they're hindered greatly by the fact that they're outside our solar system's habitable zone, where Earth sits. 

But what about gas giants in other solar systems, where planetary arrangements - and thus the moons - are completely different? According to a new study published by a team of researchers at University of California, Riverside and University of Southern Queensland, it's not only possible, but we have a number of specific exoplanets (the term for planets in other solar systems) that could have Earth-like moons.

The team looked through hundreds of exoplanets discovered by the Kepler space observatory since 2009 (or its confirmed discoveries, at least), and identified 121 gas giants orbiting within the habitable zone of their respective stars. These gaseous exoplanets, each at least three times the radius of Earth, are all very likely to amass rocky moons due to their masses.



And these "exomoons", under the right conditions, could quickly turn into great candidates for alien life. In fact, some of these moons might be even better at supporting life than the Earth: while our pale blue dot receives plenty of energy from the sun, an Earth-like exomoon would be receiving energy from both its nearby star and radiation reflected from the planet it's orbiting.

The lead author of the study, Michelle Hill from the University of Southern Queensland, talked about the implications of this new research in a press release:

Opening quote
"Now that we have created a database of the known giant planets in the habitable zone of their star, observations of the best candidates for hosting potential exomoons will be made to help refine the expected exomoon properties. Our follow-up studies will help inform future telescope design so that we can detect these moons, study their properties, and look for signs of life."
Closing quote


Unfortunately, exomoons are extremely difficult to find. We typically find exoplanets by looking for transit events, which are dips in a star's brightness that suggests a planet is passing in front of it. But it's very difficult to get a close look at the planet itself, since its size and brightness is vastly overshadowed by its star, so checking those planets for moons is an even greater challenge.

But it may be the key to finally tracking down that "second Earth" astronomers are always hoping to discover. All this time we've been looking for Earth-like exoplanets, but it hardly ever occurs to anyone that we should be looking for exomoons instead.

Especially when the moons in our own solar system are so interesting themselves.
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