“These are the first hints we are seeing of an alien world that is possibly inhabited,” Nikku Madhusudhan at the University of Cambridge told a press conference on 15 March.
Astronomers first discovered the exoplanet K2-18b in 2015, and soon established that it was a promising place to look for life. About eight times as massive as Earth and orbiting a star 124 light years away from us, the planet sits in the habitable zone of its star, where liquid water can exist.
Further observations, in 2019, found evidence of water vapour, which led to suggestions that the planet may be covered in oceans sitting under a hydrogen-rich atmosphere, though not all astronomers agreed.
In 2023, Madhusudhan and his colleagues used the instruments on the James Webb Space Telescope (JWST) to look at K2-18b’s atmosphere in near-infrared light, and again found evidence of water vapour, as well as carbon dioxide and methane.
Theory of alien life supported by molecule produced only by living organisms
But they also found a tantalising hint of dimethyl sulphide (DMS), a molecule that, on Earth, is produced only by living organisms, mainly marine phytoplankton. The signs for DMS were extremely weak, however, and many astronomers argued that we would need much stronger evidence to be certain about the molecule’s presence.
Now, Madhusudhan and his colleagues have used a different instrument from JWST, the mid-infrared camera, to observe K2-18b. They found a much stronger signal for DMS, as well as a possible related molecule called dimethyl disulphide (DMDS), which is also produced on Earth only by life.
“What we are finding is an independent line of evidence in a different wavelength range with a different instrument of possible biological activity on the planet,” Madhusudhan said.
The team claims that the detection of DMS and DMDS is at the three-sigma level of statistical significance, which is equivalent to a 3-in-1000 chance that a pattern of data like this ends up being a fluke. In physics, the standard threshold for accepting something as a true discovery is five sigma, which equates to a 1-in-3.5 million chance that the data is a chance occurrence.
It’s just chemicals discovered on this planet that are usually produced biologically on Earth. This doesn’t mean there’s life on that planet. It could just mean that there are other methods of producing these chemicals other than biologically. Some scientists aren’t even sure that these are the correct chemicals. Planet (124 LY) is too far away to send a probe, so it will all be through calculation.
yes, that’s an important caveat. we only know what earthy carbon-based life and its signs look like, with dimethyl sulfide and dimethyl disulfide being key signs because they’re only made by living organisms on earth. looking for those chemicals is our best chance of identifying extraplanatery life because we dont know what the key identifers are for acarbon-based life. it could be that we have “found” life elsewhere but we just don’t realize because it not something we’re familiar with the data we get
Thos is a false trail. We certainly may be missing signs of life that don’t follow patterns we aren’t looking for, but that has no bearing on this case. The argument in this case would be if there were paths we knew of that could produce these chemicals that don’t involve life, or paths that involve life on earth but could develop without life being present to produce these chemicals elsewhere. If we can’t rule these options, and possibly others I haven’t thought of, out, then we may only be left with alien life being the source of these chemicals.
If there was life on it, it would be very different than anything we know of.
8 times as massive as earth. Hydrogen rich exosphere, only trace amounts of water vapor.
:( I just want alien overlords already got damnit
Steps down from spaceship.
-“Make Aliens Great Again!”
Is orange.
Honestly this planet deserves an alien invasion. Please be moral aliens
