A rocky planet 48 light years from Earth has become the first world of its kind known to hold an atmosphere while orbiting inside its star's habitable zone. The discovery, led by researchers at Harvard University, marks the strongest evidence yet that Earth like planets beyond our solar system can keep the conditions needed for life.
The planet, called LHS 1140 b, orbits a cool red dwarf star. Astronomers detected its atmosphere by observing helium slowly escaping into space. The finding confirms what theoretical models had predicted: that this rocky world has held onto its atmosphere for billions of years.
Helium Leaks Reveal a Hidden Atmosphere
Collin Cherubim, who recently earned his Ph.D. in Earth and Planetary Sciences from Harvard, led the study published July 16 in the journal Science. His team used observations of helium escaping from the planet's upper atmosphere to confirm its presence. The signal matched earlier predictions that LHS 1140 b had retained an atmosphere.
The planet sits within the habitable zone of its star. This is the region where temperatures could allow liquid water to exist on a rocky surface. Scientists have found thousands of exoplanets, including several rocky ones in habitable zones. But confirming whether any of those planets actually have atmospheres has been one of the hardest problems in exoplanet research.
A Rocky World That Kept Its Atmosphere
Previous studies had identified rocky planets orbiting inside habitable zones. But this is the first time researchers have clearly shown that one of those worlds has an atmosphere that may have lasted for billions of years. Cherubim and his colleagues developed a theoretical model predicting that the upper atmosphere of LHS 1140 b would contain helium. Their observations confirmed it.
Robin Wordsworth, a professor at Harvard and one of Cherubim's advisors, noted that twenty years ago scientists wondered whether other terrestrial type planets even existed. Then they learned such planets are common and found some in habitable zones. The next question was whether any had managed to keep an atmosphere. Now researchers know at least one has.
What This Means for the Search Beyond Earth
An atmosphere is essential for a planet to support life as we know it. This discovery provides the first confirmed example of an atmosphere on a rocky world in another star's habitable zone. LHS 1140 b is now a prime target for further study. Its location 48 light years away makes it close enough for future telescopes to examine in greater detail. The finding represents a milestone step toward the discovery of Earth like rocky planets beyond our solar system.
