At the end of the year, Live Science compiled 10 scientific discoveries in 2020 about life beyond Earth. We translate it with some abbreviations and additions.
Are aliens calling us from Proxima Centauri?
Likely, the strange signals that we receive from space do not come from aliens at all. But earlier this month, researchers announced that they had caught a mysterious beam of energy at a radio frequency of 980 megahertz, emanating from a nearby star.
Around Proxima Centauri, which is only 4.2 light-years away, there is one gas giant and one rocky planet, which is 17% larger than Earth and is located in its star’s habitable zone. That is, in theory, there could be liquid water. The unexplained signal reportedly shifted slightly while observing the star, which reminded scientists of the shift caused by movement from the planet. Researchers are excited but careful in their findings. They still need to figure out if more primitive sources, such as a comet, a hydrogen cloud, or even human technology, can simulate an alien signal.
Alien bacteria can live in the clouds of Venus
In September, news broke of potential evidence for life in the upper clouds of Venus. The announcement pointed to the presence of phosphine, a rare and often poisonous gas that, at least on Earth, is almost always associated with living organisms.
It would seem that Venus, with its infernal surface temperature, incredible pressure, and clouds of sulfuric acid, is not very suitable for the existence of life. But a team of astrobiologists aimed the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimeter / Submillimeter Lattice in Chile at Venus and captured the phosphine signature in this planet’s cloudy layer of perfectly Earthy temperatures and pressures.
Terrestrial bacteria are known to thrive in rather challenging environments, so a biological explanation makes perfect sense. The research team doesn’t claim this is conclusive evidence of space bacteria, but at the very least, it would mean more funding to find life in unlikely places.
Oumuamua may still be an alien artifact
Two years ago, scientists noticed a cigar-shaped object moving through the solar system. This asteroid, dubbed Oumuamua, was thought to be the first interstellar object found in our system. But careful observation showed that Oumuamua accelerated as if something were moving him, and scientists are still not sure why.
Avi Loeb, an astrophysicist at Harvard University, theorized that the interstellar visitor could be an alien probe propelled by a light sail – a wide, thin piece of material accelerated by solar radiation. However, other scientists rightly noted that the hydrogen ice on this object could melt in the same way as when using a rocket engine or other propulsion method. But in August, Loeb “fired back” and wrote in his study that hydrogen ice heats up very easily even in the colder depths of interstellar space and must have gone from solid to gaseous before Oumuamua reached our system. It seems the debate could go on for a long time.
US authorities declassified UFO video, but don’t believe the hype
In April, the US Navy released footage from pilots of strange, wingless aircraft flying at hypersonic speeds. Despite such videos, people should still be careful, said freelance journalist Sarah Scoles in her book They’re Already Here: UFO Culture and Why We See Dishes.
Sarah decided to examine the military evidence but could not determine if there were really alien planes there. Instead, she wrote a book about why we need to believe in something other than ourselves.
The Milky Way may be teeming with oceanic worlds
Oceanic worlds, classified as having significant amounts of water on or just below the surface, are surprisingly common in the solar system. Earth is obviously one such place, but Jupiter’s moon Europa is also believed to hide vast seas under its icy shell. Saturn’s moon Enceladus is known to have water geysers erupting outside.
In fact, the intent is already brewing in the astronomical community to send a probe that could land on any of the satellites sometime in the 2030s and check if any living things can hide under their surface.
For oceanic worlds outside our solar system, in a study published in June, scientists looked at 53 exoplanets similar in size to Earth and analyzed variables including their size, density, orbit, surface temperature, mass, and distance from the star. The researchers concluded that out of 53, about a quarter might have suitable conditions to be considered ocean worlds, suggesting that such locations may be relatively common in the galaxy.
Some creatures on Earth breathe hydrogen, maybe aliens too?
Most earthlings need oxygen to survive. But oxygen is not common in space, accounting for about 0.1% of the universe’s normal mass. There is much more hydrogen (92%) and helium (7%) in space, and many planets, including gas giants such as Jupiter and Saturn, are composed primarily of these light elements.
In May, scientists took E. coli and common yeast and tried to determine if they could live in different environments. It is now known that such microbes survive without oxygen, and when placed in a flask filled with pure hydrogen or pure helium, they manage to grow, albeit at a slower pace than usual. The findings suggest that we may be looking for life in places that don’t quite look like Earth.
Life could have existed around a black hole
When hunting for life on other worlds, most scientists stick to what they know – looking for worlds the size of the Earth, orbiting stars similar to the Sun. But there can be much more exotic configurations, such as a planet orbiting and heating a black hole.
At first glance, this scenario seems absurd. But, contrary to popular belief, black holes do more than pull in everything around them. Gravitationally stable orbits are also possible, and light from cosmic background radiation – a relic with a temperature near absolute zero from the early Universe, which permeates all space – will heat up when it falls into a black hole. As shown in an article published in March, it can provide heat and energy to organisms that accidentally evolved in such a strange place.
A thousand places from where aliens could watch us
In October, researchers compiled a catalog of 1004 nearby stars that could prove good places to observe and detect life on Earth. “If observers searched [from planets orbiting these stars], they could see signs of the biosphere in the atmosphere of our pale blue dot,” says study lead author Lisa Kaltenegger, assistant professor of astronomy at Cornell University and director of the Carl Sagan Institute at university.
Using the observation instruments that astronomers use to study exoplanets, alien observers could hunt for oxygen and water in our atmosphere and possibly conclude that Earth is a good home for living organisms.
Most aliens are probably dead
People like to imagine that our galaxy is full of technological beings that can connect with us. But all cultures and civilizations experience both sunrise and sunset. Many of the inhabitants of space may have turned to dust a long time ago.
The study, published in December, indirectly confirms this theory, taking into account several important factors: the predominance of stars, in which orbits are Earth-like planets; the frequency of the deadly, destroying all supernovae; the time it takes to develop intelligent life under the right conditions; and the possible tendency of intelligent beings to self-destruct.
The analysis showed that the greatest likelihood of life appearing in the Milky Way occurred about 5.5 billion years ago, even before our planet was formed. It seems that humanity appeared too late in the galaxy, and many other inhabitants of the universe no longer exist.
We must abandon our prejudices when looking for life on other planets
The human brain has many limitations. We are misled by cognitive biases, optical illusions, and blindness to what we don’t expect to see. One question that has always plagued the search for extraterrestrial beings is whether we can recognize the life that is different from what we encounter on Earth. Scientists have long been convincing us to “expect the unexpected.” Life on other planets may not leave the same biological traces as terrestrial organisms, making it difficult to detect from our point of view.
Thus, to find aliens, you need to constantly review your own assumptions and be ready for something radically different from us.