Earth-like exoplanet LHS 1140b found to have an atmosphere

Astronomers have detected an atmosphere around LHS 1140b, a rocky exoplanet nearly 48 light-years from Earth. This discovery is a significant milestone in the search for life beyond our solar system. It is the first time an atmosphere has been identified around an Earth-like planet orbiting within its star's habitable zone, where conditions might allow for liquid water.

While atmospheres have been observed around gas giants and ice giants, and even some rocky exoplanets, those planets were typically outside the habitable zone. The composition of LHS 1140b's atmosphere may differ significantly from Earth's.

Dr. Collin Cherubim of Harvard University, the study's lead author, described the finding as "truly exciting." He believes LHS 1140b is now the most promising laboratory for studying astrobiology and habitability outside our solar system. The planet's atmosphere is thought to have persisted for over three billion years.

LHS 1140b is 5.6 times Earth's mass and 70% larger in radius. Discovered in 2017 in the constellation Cetus, it orbits a red dwarf star, smaller and dimmer than the Sun, which emits a significant amount of ionizing radiation. The planet is tidally locked, always showing the same face to its star, similar to the Moon's relationship with Earth. It may also hold more water than Earth, but its atmospheric composition is likely very different.

Currently, LHS 1140b possesses key ingredients for life: a rocky composition, temperatures suitable for liquid water, and an atmosphere that could protect the surface from radiation and prevent water from escaping. The star itself is also relatively calm with infrequent flares. Researchers detected helium escaping from the planet's atmosphere using infrared spectrograph data from the Magellan Clay telescope in Chile, confirming theoretical models predicting a helium-rich upper atmosphere.

Cherubim aims to determine the atmosphere's full composition and investigate whether the planet has surface oceans or other life-supporting features. The discovery represents a major step forward from just two decades ago when the existence of Earth-like planets was still a question.

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This is truly exciting discovery, because I think LHS 1140b is really positioning itself as the best, most promising and most interesting laboratory for studying astrobiology and habitability outside our solar system.