Astronomers have discovered the first atmosphere of a planet in the habitable zone of another star

The search for extraterrestrial life has yielded little fruit. This remains true, but scientists have some renewed hope. Astronomers have discovered for the first time an atmosphere surrounding an exoplanet within the habitable zone of its host star.

Say hello to LHS 1140b, a rocky Earth-like planet that lives about 48 light-years away from us. For reference, Voyager 1 is fast approaching Her first light day After nearly 50 years of flying. LHS 1140b is located in the “Goldilocks” zone of its star, meaning it is far enough away to be observed. It is not roasted Like Mercury, but close enough that it’s warm enough to support liquid water.

according to New study Published in the journal Science, the “special” part of this discovery is not just limited to the habitable zone around the star. It appears to meet additional criteria that scientists are interested in — namely, that it is rocky, not a gas giant, and can still hold on to an atmosphere despite extreme conditions. The atmosphere is what helps stabilize surface temperatures, which is essential for life to exist.

“It’s very exciting,” Colin Cherubim, the study’s lead author and a Harvard doctoral graduate, said in an email. “The main goal in this field has been to understand whether any rocky exoplanets can retain an atmosphere.”

Most rocky planets orbit M-class dwarf stars, which “emit high-energy radiation for a much longer period than stars like the Sun,” Cherubim says. Most rocky planets are stripped of their atmospheres fairly early in their life cycles, thanks to this radiation, the influence of the solar wind and other factors, thus eliminating their chance of hosting life.

Until LHS 1140b, Earth was the only rocky planet ever observed by humans with an intact atmosphere.

It wasn’t easy to find. Cherubim used a computer model he developed during his work that “simulates how exoplanetary atmospheres evolve over billions of years.” These models predicted the existence of “helium worlds,” or rocky planets with helium (or at least mostly helium) atmospheres. Cherubim tested his theory with LHS 1140b and struck the proverbial gold.

Is there life on LHS 1140b?

Whether or not LHS 1140b contains life is a complex question. Cherubim says 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 habitable. LHS 1140b appears to have all of these things.

The main problem is that LHS 1140b’s upper atmosphere is made up almost entirely of helium, which is also “hydrogen-depleted.” This does not bode well for life, because helium normally cannot support life as we know it here on Earth.

The Cherubim say that the planet is also tidally locked to its star, like the Moon is to Earth, meaning that one side of the planet has perpetual day and the other has perpetual night. It’s also about 70% larger than Earth, which means gravity there is almost twice as strong. These results don’t completely rule out life, but if LHS 1140b hosts life, it would certainly be very different from life on Earth.

Cherubim also acknowledges that researchers do not yet know whether the planet has a rocky surface or is completely covered by an ocean, the latter of which would be important for the search for life. Computer models developed by Cherubim predict that the lower atmosphere may contain gases more suitable for life, such as carbon dioxide, water and even oxygen.

“While we need more data to know what’s happening in the rest of the atmosphere, this may be the world’s first known helium,” Cherubim said. “The ability of these rocky worlds to retain a helium atmosphere is not only good for their habitability prospects, but it also tells us that our (computer predictive) models are getting something right.”

Until then, Mars is Most likely candidate To find signs of life, as researchers have already identified potential biosignatures in its soil.

Another potential candidate for habitability is K2-18b, where scientists have reported preliminary evidence of the presence of dimethyl sulfide, a compound typically produced by oceanic phytoplankton. Scientists are also interested in this Trappist system – 1 starWhich includes seven Earth-sized planets, three of which are located in the habitable zone around the star.