Researchers have identified over 100 planets beyond our solar system that may have moons capable of supporting life.
Using data from the Kepler space telescope, scientists identified 121 planets that orbit within the habitable zone of their star.
Each are estimated to be more than three times the width of Earth, and likely all host several large moons, according to the Daily Mail.
The new research is a collaboration between scientists at the University of California, Riverside and the University of Southern Queensland.
"There are currently 175 known moons orbiting the eight planets in our solar system," says Stephen Kane, an associate professor of planetary astrophysics and a member of the UCR's Alternative Earths Astrobiology Center.
"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.
"Including rocky exomoons in our search for life in space will greatly expand the places we can look."
Kepler launched back in 2009 and has since detected thousands of worlds outside of our solar system.
While scientists are primarily looking for terrestrial – or rocky – planets, Jupiter-like planets that sit in the habitable zone are also considered to be promising, as they may host habitable moons.
According to the researchers, exomoons may even be more favourable for life than Earth, as they receive energy from both the star and radiation reflected off the planet.
But, scientists have yet to confirm the existence of an exomoon.
The new work could help to narrow the search down, with 121 giant planets that may contain such moons.
"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," said Michelle Hill, an undergraduate student at the University of Southern Queensland who is working with Kane and will join UCR's graduate programme later this year.
"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."
WHAT IS THE GOLDILOCKS ZONE?
The habitable zone is the range of orbits around a star in which a planet can support liquid water.
This habitable zone is also known as the "Goldilocks" zone, taken from the children's fairy tale.
The temperature from the star needs to be "just right" so that liquid water can exist on the surface.
The boundaries of the habitable zone are critical.
If a planet is too close to its star, it will experience a runaway greenhouse gas effect, like Venus.
But if it's too far, any water will freeze, as is seen on Mars.
Since the concept was first presented in 1953, many stars have been shown to have a Goldilocks area, and some of them have one or several planets in this zone, like "Kepler-186f", discovered in 2014.