If there is extraterrestrial life in the galaxy, it is most likely orbiting LHS 1140b.
Astronomers have discovered that an exoplanet 48 light-years away is emitting helium into space, providing strong evidence that it has a strong atmosphere, according to a new study published in the journal Science .
And that's not all: it's also a rocky world like our own, and it orbits within its star's habitable zone—the region around a star where a planet could support liquid—and possibly habitable—water on its surface.
If their findings are confirmed, it would be the first Earth-like exoplanet ever discovered with an atmosphere stable enough to support life – and could support the belief that there are many such planets in the Universe, rather than that our own is a rare anomaly.
«"If there's one exoplanet, there are more," Sara Seager, an astrophysicist at the Massachusetts Institute of Technology who was not involved in the study, told the newspaper. New York Times . "I hope this is the beginning of something new.".
«"We have absolutely no evidence at this point for life on the planet," lead study author Collin Cherubim, a planetary scientist at Harvard University, added in an interview with the newspaper. "But we think all the really important, necessary ingredients are there.".
The discovery of exoplanets is a rare occurrence. Although we have cataloged millions of stars, we have confirmed the existence of only about 6,000 worlds outside our Solar System. Finding planets with atmospheres is even more challenging, as their signals are weaker compared to the light from the planet's star. In many cases, planets with atmospheres are gas giants, which are unlikely to support life.
A key detail is that LHS 1140b orbits a red dwarf. Planets around red dwarfs are easier to spot because these tiny stars are dimmer, making them easier to see when a planet passes in front of them. However, because they radiate less heat, a potentially habitable planet would have to orbit much closer to them than our Sun. This could be problematic, as red dwarfs are thought to be highly unstable. A planet orbiting them too closely would be at risk from solar flares and other powerful eruptions, which could strip its atmosphere and destroy any developing life forms.
However, astronomers have discovered that LHS 1140b has a helium-rich atmosphere despite—or rather, precisely because—it is located in the star's habitable zone. This demonstrates that red dwarf variability may not be as big a problem as previously thought (although this dwarf appears to be less active than its peers). As explained Science , They used a theoretical computer model of exoplanet atmospheric evolution that tracked how lighter elements like hydrogen and helium would be ejected by the host star's outbursts. Applying this model to LHS 1140b, first discovered in 2017, they predicted that its upper atmosphere would be predominantly composed of helium, a promising sign that it could support life.
«"Twenty years ago, we wondered if other Earth-like planets even existed," said Robin Wordsworth, professor of Earth and planetary sciences at Harvard, in a statement about the work. "Then we learned they're common, and we've discovered several in the habitable zone.".
«"The next question was whether any of them managed to maintain an atmosphere," he added. "Now we know that at least one did.".
More news from space: Scientists say they have discovered an Earth-like planet very close by.