Nearby Exoplanet May Have Life-Sustaining Ocean, Say Scientists
An exoplanet relatively close to Earth may be the first ever detected with a potentially life-sustaining liquid ocean outside our Solar System, according to scientists using NASA’s James Webb Space Telescope. While more than 5,000 exoplanets have been discovered, only a handful are in the “Goldilocks zone”—neither too hot nor too cold—where liquid water, a key ingredient for life, could exist.
LHS 1140 b: A Rocky ‘Super-Earth’
The exoplanet LHS 1140 b, located 48 light-years from Earth (equivalent to more than 450 trillion kilometers), is one of the few planets in this habitable zone. First discovered in 2017, it has since been a subject of intense study. Initially thought to be a small gas giant, or “mini-Neptune,” with an atmosphere too thick with hydrogen and helium to support life, new observations from the Webb telescope have confirmed it is actually a rocky “super-Earth.”
Significant findings from Webb Telescope
The exoplanet, 1.7 times larger than Earth with 5.6 times its mass, was analyzed as it passed in front of its star. The Webb telescope found no signs of hydrogen or helium, ruling out the mini-Neptune theory. Instead, the density suggests large quantities of water. According to Martin Turbet of France’s CNRS research center, this could be a significant amount of water compared to Earth, where oceans represent only 0.02 percent of its mass. For LHS 1140 b, 10 to 20 percent of its mass might be water.
Implications for liquid water and atmosphere
Whether this water exists in liquid or ice form depends on the planet’s atmosphere. Although there is no direct evidence of an atmosphere, several indicators suggest its presence. Charles Cadieux, the lead study author and a PhD student at the University of Montreal, remarked that LHS 1140 b “could well be our best bet to one day indirectly confirm liquid water on the surface of an alien world.”
The exoplanet is gently warmed by its red dwarf star, which is one-fifth the size of the Sun, potentially giving it a surface temperature similar to Earth and Mars. The presence of gases such as carbon dioxide will be crucial in determining whether the planet is covered in ice or water. One hypothesis suggests a vast liquid ocean measuring about 4,000 kilometers in diameter, around half the surface area of the Atlantic Ocean, where the planet is most exposed to its star’s heat.
Future research and observations
Webb’s instruments have suggested the presence of nitrogen, another potential ingredient for life, though further research is needed to confirm this finding. The researchers hope to secure additional observation time with the Webb telescope to gather more data on LHS 1140 b. It is estimated that confirming the exoplanet’s atmosphere will take at least a year, with another two to three years required to detect the presence of carbon dioxide. The potential discovery of a life-sustaining ocean on LHS 1140 b represents a significant step forward in our search for habitable worlds beyond our Solar System.
