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A dubious claim

You might have seen the news this week that an astronomer at the University of Cambridge is claiming to have detected proof of life on an exoplanet [New York Times, New Scientist, The Guardian]. The press have been somewhat misled by the Cambridge press release into thinking this is a near certainty, when in reality it’s probably nothing to get excited about. I’d recommend this Bluesky thread from Chris Lintott for an overview:

I thought it would be fun to make a list of some notable times people have claimed to find evidence of extraterrestrial life which turned out not to be so exciting:

• Late 19th century to early 20th century: Giovanni Schiaparelli, Percival Lowell, and others discover “canals” on Mars.

• 1976: The two Viking landers arrived on Mars and carried out experiments designed to look for life by hydrating soil samples. The results turned out to be ambiguous.

• 1996: Scientists studying the Mars meteorite Alan Hills 84001 claimed to have found the fossilised remains of bacteria. Similar fossil-like structures have since been produced in the lab without life.

• 2005: Mars again! Two scientists, Carol Stoker and Larry Lemke announced that they had found strong evidence of underground life on Mars, based on an analysis of methane in the atmosphere. This was immediately rejected as proof of life by other scientists.

• 2017: The astronomers behind the Planet Hunters citizen science project found unusual brightness fluctuations in a star, now known as Boyajian’s Star, and mentioned the an alien “megastructure” as one of a list of possible explanations. The press mostly focused on that and ignored the more plausible explanations.

• 2020: Astronomers detected spectroscopic signatures of the chemical phosphine, a potential biosignature, in the atmosphere of Venus. Despite taking excellent precautions to rule out other explanations, the claim that this is a sign of life is disputed.

• Numerous, uncountable claims by Avi Loeb (don’t get me started).

Eventually, inevitably there will be a day when someone actually does discover evidence of alien life. But unfortunately we’re not there yet.

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Solar System

• Titan has a crust made of ice, possibly with liquid water underneath. New simulations of impact craters are pinning down how thick the ice is, though they don’t exactly replicate the observed craters. [Universe Today]

• On Sunday, Lucy (the spacecraft) visited the asteroid Donaldjohanson, which is named after the paleoanthropologist Donald Johanson, who discovered Lucy (the fossil) in 1974. [NASA]

• Storms on Jupiter can rain huge, mushy ammonia snowballs, creating layers of ammonia which will stay trapped deep within the atmosphere until some future storm comes along and dredges it all back up. [Space.com]

Galaxy

• A region near the galactic centre doesn’t form as many stars as it should. New observations from JWST have found evidence that this is due to extremely strong magnetic fields. [Space.com]

• There’s a binary system 150 light years away that will eventually explode in a type Ia supernova – when a white dwarf accretes enough material to become unstable. Unfortunately we won’t get to see it as it won’t happen for another 23 billion years. [Universe Today, EarthSky, Space.com]

• JWST has captured an amazing image of the planetary nebula NGC 1514. This is the material thrown off by an aging star, and in this case the nebular has been shaped by the star being part of a binary system. [NASA, ESA, Space.com]

Universe

• The Large Magellanic Cloud is tearing apart the Small Magellanic Cloud! Astronomers used to think it was just rotating, but it looks like the stars’ motions are actually due to tidal forces. [BBC Science Focus, ScienceDaily]

• A potential solution has been found to the “missing baryon problem”, where the early Universe had twice the amount of normal matter compared with the present day. [UC Berkeley]

• Radio emissions from energised carbon monoxide are helping find quasars. The high energy levels of the carbon monoxide molecules show that it has been exposed to X-rays emitted from near a supermassive black hole. [Universe Today]

Finally

I’m loving these 3D views of the Martian terrain, courtesy of the Mars Express orbiter:

Check out the ESA website for more.

What is Three Alpha? Other than being the name of the newsletter you’re reading now, the name “three alpha” comes from the triple-alpha process, a nuclear chain reaction in stars which turns helium into carbon. Read more here.

Who writes this? My name is Dr. Adam McMaster. I’m an astronomer in the UK, where I mainly work on finding black holes. You can find me on BlueSky, @adammc.space.

Let me know what you think! You can send comments and feedback by hitting reply or by emailing [email protected].