In a year in which mysterious monoliths they literally appeared out of nowhere, you'd think the first real discovery of alien life would be a stone's throw away. And instead.
2020 brought no little green man, but it brought astronomers closer to discovering extraterrestrial life like never before. From organic molecules sprouting around the solar system to radio signals finally traced back to their source, here are some of the biggest discoveries of the year about where aliens might be (or where they definitely aren't) in the universe.
There may be alien life in the clouds of Venus...
In September, Venus became the most popular planet on Earth when scientists discovered possible traces of the molecule phosphine in the planet's atmosphere. On Earth, phosphine (one phosphorus atom and three hydrogen atoms) is mostly associated with non-oxygen-breathing bacteria, as well as some human activities. The molecule is naturally produced by gas giants, but there's no good reason it should be on the hot, hellish world of Venus, the researchers concluded. Unless, they said, there is a form of life that breathes it among the mysterious clouds of the planet.
… But that's not necessarily the case
As exciting as it was, the discovery of phosphine was met with strong skepticism from the scientific community. For starters, it's not even clear that the researchers detected the phosphine; their observations contained so much interference that there may even have been a "chemical signature" similar to phosphine, but not phosphine.
And even if the reading were accurate, phosphine could very easily be created in a totally random way through a series of geological processes that do not involve life at all. He says it Lee Cronin, chemist at the University of Glasgow in the United Kingdom. The processes that shape the red-hot surface and sky of Venus are largely a mystery, and a trace of an unexplained molecule is, sadly, not enough to confirm that alien life exists. A meaningful study of the planet is required to solve this chemical puzzle.
There may be 36 alien civilizations sharing our galaxy
How many intelligent alien civilizations are lurking among the hundreds of billions of stars in the Milky Way? According to a study published on June 15 on The Astrophysical Journal , the answer is 36.
How did the researchers come up with this number? By giving a new twist to an old puzzle known as the Drake Equation. It is named after the astronomer Frank Drake, which presented it in 1961. The equation attempts to guess the probable number of alien civilizations in our galaxy based on variables such as the average star formation rate, the percentage of stars that form planets and the (much smaller) percentage of planets which have factors compatible with life. Most of these variables are still unknown, but the authors of the new study sought to address them with the most up-to-date information available on star formation and exoplanets.
Their result? There are precisely 36 planets in the Milky Way that could host a life of intelligence similar to that on Earth. But even if the researchers pinpoint all those unknown variables, it will still take a while before we meet one of our stellar neighbors. Assuming a uniform distribution of civilizations across the galaxy, the closest is 17.000 light years from Earth.
And more than 1.000 alien stars could be watching us
Will they find us before we find them? We may find out in this lifetime. Two stars on the list host known exoplanets - on one of them we will have a direct view in 2044.
In an October 20 study in the journal Monthly Notices of Royal Astronomical Society, astronomers have calculated the number of alien star systems that have a good view of the Earth, and therefore could be observing us right now.
The team calculated that about 1000 star systems within a "radius" of about 300 light years from Earth could see our planet as it passes between their position and the Earth's sun. Any aliens observing the sky would see our sun dim as Earth passes, just like humans have done with thousands of exoplanets. Not only that: if those alien astronomers had a technology similar to ours, they could even detect traces of methane and oxygen in the Earth's atmosphere, and think “ohibò! This planet could host life ”.
Aliens are not responsible for FRBs, (at least, not this one)
Fast radio bursts, or fast radio flashes (FRB) are millisecond-long pulses of radio light that pass through space thousands of times a day. Until recently, no one had any idea what they were. Alien propulsion signals? The idea had crossed over at least the mind of an astronomer. For better or for worse, however, the idea could be put aside. In November, astronomers successfully tracked an FRB to a known source in the Milky Way for the first time ever.
The source, it turns out, was a magnetar - the highly magnetized, rapidly rotating corpse of a long-dead star.
For thousands of years after their formation, these celestial objects go through periods of violent activity, radiating powerful pulses of X-rays and gamma radiation at seemingly random intervals. Perhaps not all FRBs in the universe come from magnetars, but this discovery will help solve a decades-old mystery.
White dwarfs can be extraterrestrial strongholds
In about 4 billion years, our Sun will swell into a red giant, then collapse into a small, smoking white dwarf. An inevitable fate, and the chances of humanity fleeing to another star system are nearly impossible. But if we are still around we could find a way to take advantage of the dim light of our dead star and continue traveling as a civilization. And perhaps, suggests a paper published earlier this year in arXiv prepress database , other alien civilizations are already doing the same.
White dwarfs have been largely ignored in the search for extraterrestrial intelligence (SETI), the authors say, as a dead star is unlikely to harbor a thriving civilization. But white dwarfs sometimes have planets in their orbit, and a highly advanced civilization may be able to make their little sun work for them, even after its death. Astronomers therefore shouldn't cut white dwarfs out of their SETI equations, the authors write; indeed, maybe we should look at them first.
The aliens may not be breathing oxygen
Another underestimated target in the search for alien life: planets devoid of oxygen. Although it has long been believed that even alien life needs air to breathe, a study published May 4 in the journal Nature Astronomy argues that maybe things are different. Hydrogen and helium are much more common elements in our universe (Jupiter's atmosphere is 90% hydrogen, for example). What if an alien species evolved to breathe more?
It turns out that It could be possible. The study authors exposed a type of bacteria that does not breathe called oxygen E. E. coli coli to two different “atmospheres” manufactured inside some test tubes. One set of bottles was pure hydrogen, the other pure helium. They found that the bacteria were able to survive in both conditions, although their growth was stunted. This experiment "opens up the possibility for a much broader spectrum of habitats for life on different habitable worlds," the study author wrote in the article. Sara Seager, MIT scientist.
The aliens (probably) didn't build 'Oumuamua
Since it was spotted in 2017, the strange cigar-shaped rock called First has perplexed scientists. The object was traveling too fast to have originated in our solar system and seemed to be accelerating for no good reason. Some astronomers (especially the astrophysicist Avi Loeb Harvard University) have said it could be an alien spaceship powered by a very thin sail. Theory that met with a lot of skepticism this year, thanks to several studies describing the potential natural origins of the object.
One of the main theories? 'Oumuamua is a "hydrogen iceberg". Yes. Essentially, a solid piece of gaseous hydrogen that has drifted away from its local star and entered the frozen heart of a giant molecular cloud. After leaving the cloud core, the iceberg was 'sculpted' by radiation and molded into an elongated shape. Once it entered our solar system, then, the hydrogen began to bubble from the frozen rock, causing it to accelerate without leaving a visible trace of gas. It's a tempting theory that explains many of 'Oumuamua's quirks; however, Loeb keep believing that aliens are the most likely explanation.
In our solar system alone, four planets promise life
The first is Mars, one of the most Earth-like worlds in our solar system. Earlier this year, a large lake was detected under the southern polar cap, giving new hope that small microbes may be present there (assuming they have something to eat).
The other three candidates are all moons: Jupiter's moon Europe and the moons of Saturn Enceladus e Titan. Like Mars, Europe keeps the promise of water; its surface is a vast expanse of ice, which can hide a gigantic ocean that is more than 100 kilometers deep. Enceladus is also an icy world that could hold liquid water deep beneath its surface. Recently, gigantic geysers of water, rock particles and organic molecules have been sighted. Titan, then, is the only moon in our solar system with a substantial atmosphere rich in nitrogen, an important building block of proteins in all known life forms.
The hunt for aliens just got a little more difficult
We close with bad news (it's 2020, baby). On Tuesday 1 December, the iconic radio telescope of theArecibo Observatory in Puerto Rico has collapsed, after literally holding on to a wire for nearly five months (two different cable break incidents in August and November).
The tragic collapse ends 57 years of searching for signs of extraterrestrial life. In 1974, the telescope transmitted the now famous "Message of Arecibo", declaring humanity's technical prowess to any intelligent extraterrestrial who might be listening. There have been no answers so far, but that message to the stars inspired the 1997 film "Contact," in which the Arecibo telescope plays a starring role. The loss of the telescope leaves a gap that will not be filled easily.