Scientists have identified a planet just 25 light-years from Earth that could potentially host alien life. GJ 3378b, an exoplanet more than double the size of Earth, sits in the habitable 'Goldilocks zone' where conditions might allow liquid water to exist, according to research published in The Astrophysical Journal.
Key Findings on GJ 3378b
Astronomers at the University of California, Irvine, found that GJ 3378b's atmosphere could be the right thickness to support life. Paul Robertson, UC Irvine associate professor of astronomy and lead author, said: 'This one's exciting. It's one of our closest cosmic neighbours. 25 light-years sounds like a long way, but the Milky Way is about 100,000 light-years across, so in that respect it's our next-door neighbour.'
The rocky world orbits a red dwarf star, which is dimmer and cooler than the Sun. A year on GJ 3378b lasts just 21.5 days. 'This super-Earth gets about 90% of the radiation from its host star as Earth gets from its sun, so it's right in the sweet spot,' added Robertson. If the planet were slightly farther from this optimal zone, the star's radiation would strip away its atmosphere, similar to what happened to Mars.
Atmosphere and Habitability
Robertson explained the importance of atmospheric thickness: 'If you scale the Earth down to the size of an apple, its atmosphere would be about as thick as the skin of the apple. That's just enough to maintain the kinds of surface pressures where you can have liquid water. It's enough that there'll be breathable air and it provides maybe a little bit of protection from the harsh radiation environment of space.'
The team used the Habitable-zone Planet Finder on the Hobby-Eberly Telescope in Texas and Arizona's NEID Spectrometer on the WIYN Telescope to make their observations. While they cannot confirm whether GJ 3378b actually has an atmosphere, it remains a promising candidate for further study.
Search for Extraterrestrial Life
Earth is still the only known planet to host life, but more than 6,000 exoplanets have been discovered. Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, noted: 'Signs of life are written in a planet's light – if you know how to read it.' Her team compiled a list of 45 'Earth-like' planets in March that could potentially host extraterrestrial life.
Kaltenegger emphasized that our search for life may be limited by our own biology: 'Life on other worlds could be very different from Earth. If the planet is not much hotter or much colder (if water evaporates or freezes completely, then you need another solvent for life. We hope that the methane and ethane lakes on Saturn's moon Titan could also allow for life, but we don't know that yet.'
