The quest for extraterrestrial life hinges on the results of planetary exploration, but some scientists believe humans should be looking at moons instead.
A team of researchers from Australia and California say they have identified more than a hundred planets in the Milky Way that may have moons that could be prime targets in the search for alien life.
Their findings will also be used to help develop a powerful new telescope that will be able to look for biosignatures, or the telltale signs of life as we know it, in the moons of other planets.
Looking For Extraterrestrial Life
In a new paper published in the Astrophysical Journal, astrophysicists from the University of Southern Queensland and the University of California, Riverside say they have found 121 giant planets outside the solar system that are possibly surrounded by moons that could serve as hosts for life.
The new study is based on data collected by NASA's Kepler mission, which was launched in 2009 with the specific goal of finding Earth-like planets that are within the habitable zones of other solar systems in the galaxy.
The habitable zone is the sweet spot in the solar system where temperatures are not too hot or cold so that water can exist in all three states: solid, liquid, and gas.
Kepler's main target is to look for terrestrial planets, or planets with a rocky terrain just like Earth's. However, the researchers believe it is not time to discount gas giants just yet.
In this solar system, there are 175 known moons orbiting all eight planets. Most of them are found circling the gas giants Jupiter and Saturn, which are outside the habitable zone. In other solar systems, it is highly possible that the gas giants with rocky moons may be thriving in the habitable zone, where the conditions for life abound.
"Including rocky exomoons in our search for life in space will greatly expand the places we can look," says planetary astrophysicist Stephen Kane of the Alternative Earths Astrobiology Center of UCR.
Potential Of Finding Alien Life On Moons
The researchers say moons are prime candidates in the search for alien life. One reason is they receive light and energy from the central star in their planetary system. They also draw radiation reflected off the surface of their planets.
Although the researchers have yet to identify specific moons where life could be lurking, they have now added 121 new places to start the search. Their next goal is to identify the best exoplanets with moons that may serve as a potential seat for exploring extraterrestrial life.
In this solar system alone, the moons of giant gases are showing plenty of promise. Just recently, NASA confirmed that Saturn's moon Enceladus is home to complex carbon-rich organic molecules that are essential to life.
Enceladus has long been known to harbor all the ingredients of life. Experts have every reason to believe that the moon has a vast ocean of water hiding beneath its surface in the moon's south pole.
More than a decade ago, the European Space Agency's Herschel Space Observatory announced that it has observed giant plumes of salty water spraying into the moon's atmosphere.
These suggest hydrothermal vents exist deep in Enceladus' subsurface ocean. On Earth, similar hydrothermal vents gave birth to primordial bacteria that became the first forms of life on the planet.