The search for life in outer space, and by extension, potentially habitable planets in the galaxy and beyond has led astronomers to look at Moons of giant planets and not just planets themselves.
In this search, about 121 such potentially habitable Moons have been found, reports a paper published in the The Astrophysical Journal. The research was conducted by a team from the University of California and University of Southern Queensland. Over 100 gas giants planets were identified which could have moons that the researchers say could be good places to start looking for life.
This study was also intended to guide the future design of telescopes that can detect Moons as well as planets when looking for signs of life—biosignatures—in their atmospheres, reports Phys.org. NASA's Kepler space telescope, since it was launched in 2009 has been successful in identifying thousands of exoplanets. Kepler's primary mission is to identify exoplanets that are in the Goldilocks zone of their host stars, notes the report. The Goldilocks zone, also called the habitable zone is the space between the host star and a planet where it is possible for liquid water to exist- it is neither too hot nor too cold. The assumption being that if water exists, then life can also bloom.
Gas giants are usually looked past and rocky planets are concentrated upon because they could be similar in size to Earth and even have a similar atmosphere. Now it has come to the attention of astronomers that rocky moons of gas giants, called exomoons could also be a good target in the search for water and life.
Some of them better than Earth
"There are currently 175 known moons orbiting the eight planets in our solar system. While most of these moons orbit Saturn and Jupiter, which are outside the Sun's habitable zone, that may not be the case in other solar systems," said Stephen Kane, an associate professor of planetary astrophysics and a member of the UCR's Alternative Earths Astrobiology Center.
"Including rocky exomoons in our search for life in space will greatly expand the places we can look."
While being less common in the universe than rocky planets, about 121 such moons have so far been found. Gas giants, some of them about 3 times larger than the Earth, cannot host life, but their moons could be good for humans, sometimes even better for humans that even Earth.
This is because, say the researchers, they will receive energy from both their host star as well as radiated energy from their planet.