Scientists and ordinary people have been asking about the possibility of the existence of extraterrestrial life for more than a dozen years. Literally everything, from Spielberg-level fiction in his "ET" to the official press releases of the American aerospace agency NASA, clearly reflects how great and significant this problem is for modern man.
One of the most important sources for the existence of the life that we know is water. Therefore, it is not surprising that when we discover a new exoplanet or satellite, we try to find, first of all, its presence. Maybe, in the end, the aliens will not look the way we represent them in films and at quite serious scientific conferences, but their detection will not become less significant for the history of all mankind. And today we will talk about 10 places in the Universe where we have the most chances to find what we have been looking for for so long.
TRAPPIST-1
The discovery of a planetary system several dozen light-years away was announced earlier this year. The system consists of 7 earth-like planets orbiting an "ultracold" star, and represents an ideal target for the search for life outside the solar system at the moment.
Studying these exoplanets in the future will be relatively easy, thanks to the way they revolve around their star. These planets were discovered thanks to the transit method of observation. Using a powerful telescope, scientists tracked down when planets passed in front of their star, partially reducing its brightness in our observing instruments.
Astronomers assume that these planets have a relatively comfortable temperature, quite suitable for water to form on their surface.
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And yet, despite the fact that all exoplanets of this system are considered as potential candidates for habitable worlds, specifically three TRAPPIST-1 planets may be best suited for this role, since they are located in the habitable zone of the star. This is the area around the star, where water could be contained in liquid form on the surface of existing earth-like planets.
Titanium
The largest satellite of Saturn, the sixth planet from the Sun. This moon is being seen as a potential candidate for an inhabited world, but perhaps not in the way we might think. The satellite doesn't quite fit the description of the world in the habitable zone. But it has water and other liquids on it. It just doesn't have liquid water on it. The water on this planetary object is represented in the form of ice - temperatures are very low there.
However, the liquids there are composed of hydrocarbons. A hydrocarbon is a chemical compound of hydrogen and carbon in varying proportions. On Earth, the most common types of hydrocarbons are methane and propane gases. This may be a key factor in imagining life on Titan from a completely different perspective. It is possible that the life forms potentially present there will not survive in liquid water conditions, but they will feel quite comfortable in the hydrocarbon environment.
Despite the fact that science still has some questions (for example, about whether life is capable of existing not only in water), scientists are not going to reject the possibility of life on Titan.
Europe
One of the moons of the solar system's gas giant, Jupiter. Another candidate for the role of an inhabited world, because there is water there, which, at least according to our theories, can be contained in a liquid state. Astronomers are confident that Europe has all the necessary ingredients for life: it has water, energy sources and the correct chemical composition of the environment. The water, according to our best guess, is hidden under the thick ice crust that makes up Europa's surface.
Scientists began to talk about the possibility of direct research of Europe relatively recently. Earlier this year, it was announced that a Europa Clipper mission was to be launched within the next few years. Within its framework, a spacecraft will be sent to the satellite of Jupiter, which will explore and photograph the surface of Europa. This will happen many times. Scientists thus want to be able to analyze the characteristics of the satellite from all sides, and at the same time look for signs of life on it.
Mars
Our red neighbor. The fourth planet from the Sun. Arguably one of the most talked about likely candidates for inhabited worlds and potentially the first target of human colonization. Despite skepticism, this planet is the most likely place where we will find life.
It is clear that she will not be represented as green men or any other intelligent forms. However, the NASA aerospace agency, exploring the surface of the planet with its rovers, has found evidence that at least microscopic life could and can still exist here.
The findings indicate that in the past, the now completely dry planet had true streams and rivers of water. Relying on this, we can at least assume that life on it could somehow survive. Perhaps, as part of further research on Mars, scientists will find water in liquid form, and not only in the form of ice caps at the planet's poles.
Enceladus
Another of the many moons of Saturn, considered by astronomers as a potentially habitable world, which, unlike its hydrocarbon brother Titan, is most likely rich in water. This water, as in Europa, is hidden under a thick ice crust of the surface. Again, this could mean the likelihood of at least microbes.
Previously, the presence of water on Enceladus was considered only an assumption. At least such hope was given by the data obtained in 2015 using the Cassini spacecraft. Earlier this year, this hope was greatly increased when the apparatus found hydrogen molecules near the satellite, indicating the presence of chemical reactions taking place below its surface. Presumably, in the framework of these reactions, the ocean water of Enceladus interacts with the deep rock, as a result of which energy is produced that could be useful for living organisms.
Kepler-186f
Kepler-186f is an exoplanet orbiting the star Kepler-186, about 500 light-years from Earth. Discovered in 2014, it became the first known terrestrial planet outside the solar system to orbit within its star's habitable zone.
Less than 10 percent larger than Earth, this planet is also the most similar in size to our home among all the exoplanets discovered. Its other characteristics, such as density, are still unknown to us. But given its size, one can safely assume that this is a rocky world.
So far, the only features that allow Kepler-186f to be included in the list of potential candidates for habitable worlds are its size and location in the star's habitable zone. We also do not know anything about the presence of water on it, just as we do not know about the temperature on its surface.
Kepler-452b
According to NASA itself, the planet Kepler-452b "could be one of the best targets for the search for extraterrestrial life." However, it will be difficult to explore this planet. If only because it is located at a distance of more than 1000 light years from Earth. But despite this, scientists are almost certain that Kepler-452b is inside the habitable zone of its star, like several other exoplanets of this system.
For some time, Kepler-452b was considered by astronomers as the planet closest in size to Earth. Later this honor went to Kepler-186f. However, the very star of the system, where Kepler-452b is located, looks more like our Sun. This is probably why Kepler-452b is now one of the objects of study by the SETI Institute, which searches for extraterrestrial life.
LHS 1140b
This "super-Earth" was discovered quite recently. Scientists have found that it is in the habitable zone of the star, and are considering it as one of the most likely candidates for the discovery of extraterrestrial life.
This super-Earth is about 10 times more massive than our home. Astronomers believe that the class of planets belonging to super-Earths is represented by rocky planets, however, it is not yet possible to confirm this without accurate observations. Even so, LHS 1140b is the real mother of all super-Earths. Scientists are convinced that the planet is rocky, has an iron core … and possibly living aliens on its surface.
It is only 40 light-years away and therefore an excellent target for sending messages that could attract the attention of intelligent life, if it is there. In addition, the location of the LHS 1140b relative to the Earth and its slower rotation speed make it easier to observe it.
Star Tabby
Around the star Tabby, or KIC 8462852, a lot of controversy flared up about the likelihood of the presence of some kind of "alien megastructure" near it. Located nearly 1,500 light-years from Earth, this star was first discovered by astronomer from Yale University Tabetha Boyajian and immediately attracted the attention of scientists with its unusual behavior. The brightness of the star changes from time to time so strongly that this phenomenon cannot be explained by the usual presence of an exoplanet in the region. Therefore, among other assumptions trying to explain a similar phenomenon, of course, there is an option with aliens.
Allegedly, a super-developed extraterrestrial civilization could build a special device around the Tabi star that collects its energy and converts it into something more useful. When a star loses energy, it flickers. Therefore, the idea of an extraterrestrial cosmic megastructure of aliens has a certain amount of meaning.
However, the most recent and likely theory trying to explain the extremely unusual behavior of the star Tabi is the assumption that it is eating one of its exoplanets. It sounds no less interesting, I must admit. Nevertheless, the idea of aliens has not yet been completely discarded.
Ganymede
Another of the moons of Jupiter, on which there may be life. Like other moons, Ganymede is suspected of having a subsurface ocean. And in such a volume that it can contain even more water than on Earth. Interestingly, observation of the surface of Ganymede showed signs that liquid water once flowed through it, seeping through cracks in the satellite's ice crust.
The study of this satellite even led to the development of a new scientific method of research. For example, when analyzing magnetic fields, scientists found that from this information, you can deduce some idea of the internal structure of the satellite, including data on the presence of liquid water under its surface.
At the moment, Ganymede is not exploring any spacecraft. However, in 2022, it is planned to send Jupiter Icy Moon Explorer, or simply JUICE, to it, an interplanetary autonomous station, which, having reached Jupiter sometime by 2030, will study its system.
NIKOLAY KHIZHNYAK