GoKawiilThe search for life beyond Earth has borne little fruit. That remains true, but scientists have some renewed hope. For the first time, astronomers discovered an atmosphere surrounding an exoplanet within the habitable zone of its host star.
Say hello to LHS 1140b, an Earth-like rocky planet that lives approximately 48 light-years away from us. For reference, Voyager 1 is rapidly approaching its first light day after nearly 50 years in flight. LHS 1140b sits in the "Goldilocks" zone for its star, which means it's far enough away to not get roasted like Mercury, but close enough that it gets warm enough to support liquid water.
According to a new study published in Science, the "special" part of this discovery is not just the habitable zone around a star. It's that it seems to meet extra criteria that scientists care about -- i.e., it's rocky, not a gas giant, and can still hold onto an atmosphere despite harsh conditions. An atmosphere is what helps stabilize surface temperatures, which is essential for life to exist.
"It's very exciting," said Collin Cherubim, lead author on the study and a PhD graduate from Harvard, in an email. "A major goal in the field has been to understand whether any rocky exoplanets at all can retain atmospheres."
Cherubim says that most rocky planets orbit M-class dwarf stars, which "emit high-energy radiation for far longer than stars like the sun." Most rocky planets are stripped of their atmospheres fairly early in their life cycles, thanks to this radiation, the stripping effect of solar wind and other factors, thereby eliminating their chance to host life.
Until LHS 1140b, Earth was the only rocky planet that humans had ever observed with an intact atmosphere.
It wasn't easy to find. Cherubim used a computer model he'd developed during his work that "simulates how exoplanet atmospheres evolve over billions of years." Those models predicted the existence of "helium worlds," or rocky planets with helium atmospheres (or at least mostly helium). Cherubim tested his theory with LHS 1140b and struck proverbial gold.
Mars is still the best chance humans have at discovering life on another planet. NASA/JPL-Caltech
Is there life on LHS 1140b?
Whether or not LHS 1140b contains life is a complicated question. Cherubim says that science recognizes three main requirements for a planet to support life: an atmosphere, the right temperatures to sustain liquid water, and a mostly rocky planet to make it hospitable. LHS 1140b appears to have all of those.
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