00:00We might have just found the strongest evidence for life ever, but that's a big maybe.
00:04This is K2-18b, a planet around 124 light years away from Earth and about 2.6 times the size
00:10orbiting in the habitable zone of its solar system, the sweet spot between hot and cold
00:14where liquid water could exist, which already sounds kind of exciting. Scientists had already
00:18determined that K2-18b had an atmosphere made up of methane and CO2, but now astrophysicists
00:23at the University of Cambridge have found something else. Using NASA's James Webb Space Telescope,
00:27researchers carried out a process called transit spectroscopy, which genuinely always surprises
00:31me that it works as well as it actually does. When a planet transits in front of its star,
00:36starlight passes through the planet's atmosphere, where different chemicals absorb and remove
00:39different wavelengths of light before they reach our telescopes 120-ish years later. By comparing
00:44this filtered light to the normal spectrum of a star, we can identify which wavelengths have been
00:48removed, and that tells us what gases must be present in the planet's atmosphere, kind of like
00:53an atmospheric fingerprint. What researchers found was a gas called DMS, or dimethyl sulfide.
00:58The exciting part is that on Earth, DMS is only made by living organisms, mostly plankton in our
01:04oceans. But before we get our hopes up too high, there's a few things that could mean that this
01:07isn't our first meeting with gases emitted from ET. Firstly, getting a high accuracy on these signals
01:14is really hard. The atmosphere of an exoplanet is about the same thickness relative to the planet as the
01:19skin of an apple is relative to the whole apple. It's also 120 light years away, and we are detecting
01:25its passage across a star that is 40 times larger than it. At the moment, we're at three sigma of
01:30detection, which means we're confident to about 99.7%. But even if DMS is fully confirmed, the
01:36important part of the sentence was that DMS is a sign of life on Earth. In 2024, we found DMS
01:42on the
01:42comet 67P, which was obviously devoid of life and had been hurtling through the cold vacuum of space for a
01:47long time. Last year, scientists also showed that DMS can be produced by UV rays hitting exoplanets
01:52with thin atmospheres, which is why we don't find DMS abiotically produced on Earth because our
01:57atmosphere blocks UV. Now, this isn't to take away from the unbelievable levels of scientific achievement
02:02needed to push the boundaries of our understanding here, but we might just be being a bit too Earth-centric.
02:07Just because it smells like life doesn't mean anyone's home. If you like science and sometimes
02:10mistakes base burps for intelligent life, follow for more.
Comments