Scientists have discovered the first atmosphere around a rocky exoplanet located in its star's habitable zone. This planet, named LHS 1140 b, is about 48 light-years away. The habitable zone is the area around a star where temperatures could allow liquid water to exist on a planet's surface.
An atmosphere is crucial for life as we know it. This discovery makes LHS 1140 b a prime candidate for searching for life outside our solar system. The planet is much larger than Earth, weighing about 5.6 times as much and being 1.7 times wider. It orbits a red dwarf star every 24.7 days.
Using the Magellan Clay telescope in Chile, researchers observed the planet passing in front of its star. As starlight shone through the planet's edge, they detected helium in its atmosphere by looking at how it absorbed specific light wavelengths. A smaller planet nearby, LHS 1140 c, did not show a similar atmosphere.
Even though the star's radiation causes helium to escape, scientists believe the atmosphere has lasted for at least three billion years. Previous observations with the James Webb Space Telescope had ruled out a thick, hydrogen-based atmosphere but suggested other gases might be present.
An atmosphere protects a planet by blocking harmful radiation, controlling temperature, and maintaining pressure for liquid water. This finding, published in the journal Science, answers a long-standing question for astronomers about whether rocky planets in habitable zones can retain atmospheres.