Astronomers have found new clues to the habitability of the "big sisters" of the earth. Astronomers have found new hints of the habitability of the "big sisters" of the earth He will find everyone

Astronomers announce the discovery of a new exoplanet Kepler-186F. Its size is comparable to the size Earth, and it revolves around its star within habitable zone. Without a doubt, this is an important discovery, but it is still premature to call it historical. At the moment, there is no reason to assert that the world of the "terrestrial type" is open. It is possible that the conditions on the new planet are unacceptable for the existence of life.

Back in 2011, the Discovery website published a series of articles predicting that the discovery of 2.0 would likely take place in 2012. In one of the publications, it was said that by this time enough time would have passed for the Kepler space telescope (NASA) to detect the first exoplanet like Earth in history. At the same time, its orbit will have to be within the habitable zone, that is, where water can exist in a liquid state on a rocky surface. It is worth noting that liquid water is present on the surface of the Earth and that is why life exists here. Thus, in the search for extraterrestrial life, it is fundamentally important to find water in a liquid state.

Alas, these predictions did not come true. And although during this period, indeed, a lot of information was collected about exoplanets, nevertheless, there was no terrestrial analogue among them. And today, when more than two years have already passed after the appointed time, a worthy candidate for the title of "Earth 2.0" has finally been found at a distance of about 500 light years.

Before that, Kepler-62f was considered the planet most similar to Earth, but Kepler-186F surpasses it in all characteristics. As David Charbonneau, professor at the Harvard-Smithsonian Center for Astrophysics, said in an interview: “Now we can point to the starry sky and say that there really are planets very similar to Earth.”

Why Kepler-186F? What is special about it?

In doing its job, the Kepler telescope observed a tiny patch of sky into the constellation Cygnus, studying the luminosity of 150,000 stars. At this time, the sensitive optics of the telescope recorded a slight decrease in brightness - a phenomenon called "transit" in astrophysics. Such an event suggests that a planet is drifting in front of the disk of one of the stars. Many exoplanets have been discovered by the transit method, so scientists often claim that the "golden age" of exoplanetary research has begun.

Finding planets with terrestrial characteristics is a difficult task. But the case of Kepler-186F confirms that this is possible even if the celestial body is several hundred light-years away. Kepler-186F orbits a star that is classified as a red dwarf. The circulation period is 130 days. The size of the planet is only 10 percent larger than the size of the Earth. At the same time, its orbit is located on the outer edge of the habitable zone.

Artistic images accompanying the astrophysicists' announcement demonstrate that Kepler-186F is indeed perceived as the planet that gave birth to life. So, on its surface, there is probably an ocean and tree-like vegetation. This is a world with a dense atmosphere and white fluffy clouds. The idea that these colorful images convey is that a planet in another part of the galaxy is capable of supporting life in the same form as not Earth.

At the same time, the solar system is an excellent example that biologically dead planets can also be found in the habitable zone along with the living world. In this case, it is and . Scientists are actively searching for at least some signs of the existence of basic life forms on Mars, but too thin an atmosphere and high levels of radiation make it not a very cozy place. As for Venus, which is almost the same size as the Earth, its acidic atmosphere and the strongest greenhouse effect literally destroy water molecules. Thus, despite the presence of Venus and Mars in the "habitable zone", there is no reason to say that they are habitable.

Scientists, answering the question of whether Kepler-186F actually has white fluffy clouds and pine trees along the coastline, answer that this is not yet known. Currently, there is no means to study the atmosphere of this fascinating but distant world, let alone to conclude whether there is life or the potential for its development.

In a NASA press release, scientist Thomas Barclay explains that "being in a habitable zone does not mean that the planet is habitable." The level of temperature on the surface of the planet is essential, and it directly depends on the composition of the atmosphere. The scientist says that "Kepler-186F can be considered as a cousin of the Earth, but not as a twin brother."

In the future, it is planned to create and use space telescopes that will be able to study their atmosphere simultaneously with the observation of planets. But until then, scientists won't know if Kepler-186F is like Earth, or if it's like barren Mars and Venus. It is possible that the properties of this exoplanet are far from any other objects in the solar system.

All talk of Kepler-186F as an "Earth-like" planet is just words, as scientists admit that they are not in a position to give a conclusion about life on a planet that is so far from Earth. At the same time, Kepler-186F is an excellent stimulus for the development of interstellar research. It is this planet that will be the main target of future NASA observations.

Astrophysicists note with a smile that the world press vying with each other publishes materials about the discovery of Kepler-186F, and the term “earth-like planet” is present in the headlines. Scientists admit that this sounds encouraging, but is not a scientifically proven fact.

A planet on which life can originate must meet several specific criteria. To name a few, it must be at a distance from the star, the size of the planet must be large enough to have a molten core, and it must also have a certain composition of "spheres" - lithosphere, hydrosphere, atmosphere, etc.

Such exoplanets outside our solar system can not only support the life that originated on them, but they can also be considered as some kind of "life oases" in the universe, if suddenly humanity has to leave their planet. According to the state of development of science and technology today, it is obvious that we have no chance of reaching such planets. The distance to them is up to several thousand light years, and, based on modern technology, a journey of only one light year would take us at least 80,000 years. But with the development of progress, the advent of space travel and space colonies, there will probably come a time when it will be possible to be there for a very short time.

Technology does not stand still, every year scientists find new means of searching for exoplanets, the number of which is constantly growing. Below we show you some of the most habitable planets outside the solar system.

Kepler-283c

The planet is located in the constellation Cygnus. The star Kepler-283 is 1700 light-years from Earth. Around its star (Kepler-283) the planet revolves in an orbit about 2 times smaller than the Earth around the Sun. But researchers believe that at least two planets (Kepler-283b and Kepler-283c) revolve around the star. Kepler-283b is closest to the star and is too hot for life to exist.

But still, the outer planet Kepler-283c is located in a zone favorable for the maintenance of life forms, known as the "habitable zone". The radius of the planet is 1.8 Earth radii, and a year on it will be only 93 Earth days, which is exactly how much this planet needs to complete a revolution around its star.

Kepler-438b

Exoplanet Kepler-438b is located in the constellation Lyra at a distance of about 470 light-years from Earth. It revolves around a dwarf red star, which is 2 times smaller than our Sun. The diameter of the planet is 12% larger than the diameter of the Earth, and it receives 40% more heat. Due to its size and distance from the star, the average temperature here is around 60ºС. It's a bit hot for a human, but perfectly acceptable for other life forms.

Kepler-438b completes a full circle in its orbit every 35 days, which means that the year on this planet lasts 10 times less than on Earth.

Kepler-442b

Like Kepler-438b, Kepler-442b is located in the constellation Lyra, but in a different solar system, which is located further in the universe, at a distance of about 1100 light-years from Earth. Scientists are 97% sure that the planet Kepler-438b is in the habitable zone, and every 112 days it makes a complete revolution around a red dwarf, whose mass is 60% of the mass of our Sun.

This planet is about a third larger than Earth and receives about two thirds of our sunlight, indicating that the average temperature there is around 0ºC. There is also a 60% chance that the planet is rocky, which is necessary for the evolution of life.

Gliese 667 Cc

The planet GJ 667Cc, also known as Gliese 667 Cc, lies in the constellation Scorpio, about 22 light-years from Earth. The planet is about 4.5 times the size of Earth and takes about 28 days to complete an orbit. The star GJ 667C is a red dwarf that is about a third the size of our Sun and is part of a three-star system.

This dwarf is also one of the closest stars to us, only about 100 other stars are closer. In fact, it is so close that people from Earth can easily see this star with telescopes.

HD 40307g

HD 40307 is a dwarf orange star that is larger than red stars but smaller than yellow ones. It is 44 light years away from us and is located in the constellation of the Painter. At least six planets revolve around this star. This star is slightly less powerful than our Sun, and the planet that is in the habitable zone is the sixth planet - HD 40307g.

HD 40307g is about seven times the size of Earth. A year on this planet lasts 197.8 Earth days, and it also rotates around its axis, which means that it has a day-night cycle, which is very important when it comes to living organisms.

K2-3d

The star K2-3, also known as EPIC 201367065, lies in the constellation Leo and is about 150 light-years from Earth. It may seem that this is a very large distance, but, in fact, this is one of the 10 stars closest to us that have their own planets, therefore, from the point of view of the Universe, K2-3 is very close.

Around the star K2-3, which is a red dwarf and half the size of our Sun, three planets rotate - K2-3b, K2-3c and K2-3d. The planet K2-3d is the furthest from the star, and it is in the habitable zone of the star. This exoplanet is 1.5 times the size of Earth and makes a complete revolution around its star every 44 days.

Kepler-62e and Kepler-62f

More than 1200 light-years away in the constellation Lyra are two planets - Kepler-62e and Kepler-62f, and they both revolve around the same star. Both planets are candidates for birth or life, but Kepler-62e is closer to its red dwarf star. The size of 62e is about 1.6 the size of the Earth and it takes 122 days to revolve around its star. Planet 62f is smaller, about 1.4 times the size of Earth, and makes a complete revolution around the star every 267 days.

The researchers believe that due to favorable conditions, it is likely that water is present on one or both exoplanets. They can also be completely covered in water, which is good news, as it's entirely possible that this is how Earth's history began. According to one recent study, billions of years ago, the Earth's surface may have been 95 percent covered in water.

Kapteyn b

Orbiting the red dwarf Kapteyn is the planet Kapteyn b. It is located relatively close to Earth, only 13 light years away. The year here lasts 48 days, and it is in the habitable zone of the star. What makes Kapteyn b such a promising candidate for possible life is that this exoplanet is much older than Earth, at 11.5 billion years old. This means it formed just 2.3 billion years after the Big Bang and is 8 billion years older than Earth.

Since a large amount of time has passed, this increases the likelihood that life exists there at the present time or will appear at some point in time.

Kepler-186f

Kepler-186F is the first known exoplanet with a probable ability to support life. It was opened in 2010. She is sometimes referred to as "Earth's cousin" due to the resemblance. Kepler-186F is located in the constellation Cygnus at a distance of about 490 light-years from Earth. It is an eco-planet in a system of five planets orbiting a fading red dwarf.

The star is not as bright as our Sun, but this planet is 10% larger than the Earth, and it is closer to its star than we are to the Sun. Due to its size and location in the habitable zone, scientists believe it is possible that there is water on the surface. They also believe that, like Earth, an exoplanet is made up of iron, rock, and ice.

After the planet was discovered, researchers looked for emissions that would indicate that extraterrestrial life exists there, but so far no evidence of life has been found.

Kepler 452b

Located about 1,400 light-years from Earth in the constellation Cygnus, this planet is referred to as Earth's "big and big cousin" or "Earth 2.0". Planet Kepler 452b is 60% larger than Earth and farther away from its star, but receives about the same amount of energy as we get from the Sun. According to geologists, the planet's atmosphere is probably thicker than Earth's, and it likely has active volcanoes.

The force of gravity on the planet is probably twice that on Earth. For 385 days, the planet makes a revolution around its star, which is a yellow dwarf, like our Sun. One of the most promising features of this exoplanet is its age - it was formed about 6 billion years ago, i.e. it is about 1.5 billion years older than Earth. This means that a sufficiently long period has passed, during which life could have originated on the planet. It is considered the most likely habitable planet.

In fact, since its discovery in July 2015, the SETI Institute (a special institution for the search for extraterrestrial intelligence) has been trying to establish contact with the inhabitants of this planet, but so far has not received a single response message. No wonder, because the messages will reach our "twin" only after 1400 years, and in a good case, in another 1400 years we will be able to receive an answer from this planet.

Analyzing information from the Kepler space telescope, astronomers have for the first time discovered an Earth-like exoplanet orbiting in a zone suitable for liquid water. The discovered exoplanet has been named Kepler-186f. This discovery confirms long-standing assumptions that there may be worlds similar to Earth's in the universe. Most of the previously discovered planets in the habitable zone were at least 40 percent larger than the Earth, which naturally made it very difficult to compare them.

Exoplanet Kepler-186f is located in the star system Kepler-186, approximately 500 light-years from Earth in the constellation Cygnus. There are also four other planets in the star system, and their star has half the size and mass of the Sun, classified as a class M star, i.e. red dwarf. Red dwarfs are approximately 70 percent of all stars in the Milky Way. Not surprisingly, the first Earth-like planet was discovered just around such a star.

“The discovery of exoplanet Kepler-186f is a significant advance in the search for worlds like our Earth. Future research missions such as the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope should find the closest rocky exoplanets to us and determine their composition and atmospheric conditions. So far, we know of only one planet on which life exists - this is our Earth. Therefore, when we look for planets similar to the Earth, we automatically try to compare them. But as Earth-like as exoplanets are, finding one in the habitable zone is a significant step forward.”

To date, the dimensions of the planet Kepler-186f are known, but the mass and composition are not. However, previous observations have shown that it is likely to be solid. An exoplanet revolves around its star every 130 days and receives from it one third of the energy that the Earth receives from the Sun. Thus, the researchers found that Kepler-186f is closer to the outer edge of the habitat. If we stood on the surface of this exoplanet, then the hottest noon would look like an Earth evening on it an hour before sunset.

“Being a planet in a habitable zone does not mean that life can exist on it, since the temperature on its surface directly depends on what kind of atmosphere it has. Kepler-186f is more of a relative of the Earth than a twin, as it has some Earth-like properties,” Thomas Barclay, Ames Research Center scientist.

The remaining four exoplanets around the star, named Kepler-186b, Kepler-186c, Kepler-186d and Kepler-186e, fly around the star in 4, 7, 13 and 22 days, respectively, due to their proximity to it, which makes them automatically unusable. for life due to too high a temperature. In sum, these four planets are only one and a half times more massive than the Earth.

The next step the researchers want to take is to search for Earth's twin planet, a special kind of Earth-sized exoplanet orbiting a sun-like star.

The new data provide additional evidence for the habitability of exoplanets Kepler-62f and Kepler-186f. Most likely, their axis of rotation does not experience large fluctuations, which means a stable climate. Such conclusions are presented in a scientific article published in the Astronomical Journal by Yutong Shan and Gongjie Li from Harvard University.

Recall that the planet Kepler-62f for a long time remained the world closest to Earth in size in the habitable zone (that is, at such a distance from the star that water can exist on the surface in a liquid state). In diameter, it differs from the Earth by only 40%. It is located 1200 light years from Earth in the constellation Cygnus. As the name implies, Kepler-62f is the fifth planet discovered by the star Kepler-62. (Recall that b, c, and so on are assigned to worlds in order of discovery.)

The world of Kepler-186f, discovered in 2014, pushed Kepler-62f from the first place. Still, because the radius of the planet is only 10% larger than that of the globe. It is also in the habitable zone. According to experts, the parent star, when observed from the surface of Kepler-186f at noon, has the same brightness as the setting sun we are used to. At the same time, a year on it is 130 Earth days. By the way, the planet is located 500 light years from Earth in the constellation Cygnus.

Shan and Li set out to find out how stable the axis of rotation of these planets is. Does it oscillate relative to the plane of the orbit, or does it maintain a constant angle? If it fluctuates, then on what scale?

What does this setting affect? Recall that it is the tilt of the earth's axis that causes the change of seasons. He is "guilty" of the fact that the same point on the earth's surface at different times receives a different amount of sunlight. The earth's axis oscillates with a period of about ten thousand years: the angle it makes with the perpendicular to the plane of the orbit varies from 22.1 to 24.5 degrees. As paleoclimatologists are well aware, this periodicity gives rise to a corresponding cycle.

There is an example of a planet in which the mentioned angle changes very significantly. It's about Mars. And such inconstancy of the climate was one of the reasons that it turned into the current barren desert, in which scientists are stubbornly and so far unsuccessfully looking for at least.

"Mars is in the habitable zone of our solar system, but its axial tilt is very unstable, ranging from zero to 60 degrees," Li explains in a press release. "This instability likely contributed to the evaporation of surface water."

Why did this happen to Mars and not to Earth? Both planets act on each other with their gravity, in addition, Venus also affects each of them. This forces the plane of their orbits to oscillate periodically. And for Mars, this period coincides with the period of oscillation of the axis of rotation. These two movements are in resonance, so the first of them increases the amplitude of the second.

In the case of the Earth, due to the presence of a massive satellite (the Moon), the period of oscillation of the axis of rotation is different from that of the oscillation of the plane of the orbit. The two movements do not resonate, and the amplitude of the first of them remains small.

“Mars is located inside the “life zone” of the solar system, but at the same time its axis is very unstable - its inclination can vary from zero to 60 degrees. “escaped” into space,” explains Gongjie Li from the Harvard-Smithsonian Astrophysical Center (USA).

In recent years, scientists say the Kepler telescope and a number of ground-based observatories have discovered thousands of planets outside the solar system. Most of them turned out to be "hot Jupiters", large gas giants, or "super-Earths" - rocky planets, whose mass is 1.8-3 times that of the earth.

How the large "cousins" of the Earth are formed is still largely a mystery to scientists, since so far planetary scientists have not been able to find a single newborn star system where such planets would arise. This makes it difficult to assess whether they can support life, or whether the extreme pressures, temperatures, or other factors inherent in such objects necessarily render them lifeless.

Li and his colleagues uncovered one of the most important characteristics of these planets by observing the planet Kepler-186f - the first "super-Earth" in the history of astronomy, the discovery of which NASA scientists announced in April 2014.

This planet is located in the constellation Cygnus, at a distance of about 560 light-years from Earth, thanks to which it and its "neighbors" - the five other worlds of the Kepler-186 system - can be observed using Hubble and many powerful ground-based telescopes.

The gravitational interactions of Kepler-186f with other planets of this stellar family, as the scientists explain, will periodically shift its axis, causing it to “wobble”. The strength of these wobbles can be different - for example, the angle of inclination of the Earth's orbit has always been from 21 to 24 degrees, while the axes of rotation of Mars and Venus were shifted by 60 and 180 degrees in the distant past.

Such fluctuations can be calculated by observing how the planets move, how they are arranged in a star system, and how strongly they attract and repel each other, Li said. Using data from Kepler and Hubble, his team calculated how much Kepler-186f's axis has wobbled over the past ten million years.

It turned out that even in the absence of satellites like the Moon, which prevents shifts in the Earth's orbit, the "rocking" of the Kepler-186f axis should not exceed about two degrees. Similar changes, as shown by calculations, should be characteristic of the planet Kepler-62f, another super-Earth from the "life zone" in the constellation Lyra.

Such calculation results suggest that the climate and conditions on such planets should be much more stable than previously thought by scientists who assumed that a satellite the size of the Moon was required to stabilize them. All this, Li and his colleagues conclude, significantly increases our chances of finding intelligent or non-intelligent life on Earth's "big sisters".