An artist’s illustration of a potentially habitable exomoon orbiting a giant planet in a distant solar system. Credit: NASA GSFC: JAY FRIEDLANDER AND BRITT GRISWOLD
The ongoing pursuit to find life outside of Earth now includes 121 new giant planets that could have habitable moons.
A team from the University of California-Riverside (UCR) and the University of Southern Queensland has found a group of 121 planets using NASA’s Kepler telescope that could possibly have habitable moons, a discovery that could lead to newly designed telescopes capable of detecting the potential moons and identifying telltale signs of life called biosignatures in their atmospheres.
Scientists have identified thousands of exoplanets—planets outside of our solar system—following the launch of the Kepler telescope in 2009. The primary goal of the Kepler mission was to identify planets that are in the habitable zones of their stars—where it is neither too hot nor too cold for liquid water and for potential life to exist.
One potential target in the pursuit of life elsewhere is terrestrial or rocky planets because some may be geologically and atmospherically similar to Earth.
From the Kepler mission, scientists also focused on gas giants, which may not be candidates for life themselves, but their harbor rocky moons called exomoons could possibly sustain life.
“There are currently 175 known moons orbiting the eight planets in our solar system,” Stephen Kane, an associate professor of planetary astrophysics and a member of the UCR’s Alternative Earths Astrobiology Center, said in a statement. “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.”
The 121 planets identified all have orbits within the habitable zones of their stars.
The gas planets are more than three times the radii of the Earth and less common than terrestrial planets. However, each gaseous planet likely hosts several large moons.
Scientists have long believed that exomoons— which have not been confirmed in the discovery— could provide a favorable environment for life, possibly even better conditions than on Earth because they receive energy from both their star and from radiation reflected from their planet.
“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,” Michelle Hill, an undergraduate student at the University of Southern Queensland who is working with Kane and will join UCR’s graduate program in the fall, said in a statement. “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.”
The study was published in The Astrophysical Journal.
