They discovered a planet similar to the earth. New Earth-like exoplanet discovered: space neighbor

Since the 18th century, scientists have believed that life and mind are ubiquitous in the Universe, and not only planets and moons are inhabited, but even stars, including our Sun. Over time, such maximalism had to be abandoned, but there was still hope for the habitability of Venus and Mars. Astronomers have even found "confirmation" of the existence of aliens: for example, "channels" on Mars.

In the 1960s, when research vehicles went to the planets, it turned out that neighboring worlds were not adapted for life, and even if it was there, it was not in a developed form. A sad period of "cosmic loneliness" began in the history of mankind: for twenty years, even the presence of planets in other stars was questioned.

Photo of the surface of Venus, transmitted by the Soviet probe Venus-13 (before the probe broke from the high temperature). Enjoy your colonization!

The first exoplanet, the existence of which was confirmed at once by two independent research groups, was discovered in 1995. It was "hot Jupiter" near the 51st Pegasus, which recently received official name Dimidium. Currently, 3518 planets have been discovered in 2635 planetary systems, and they are very diverse. However, both scientists and the public pay the greatest attention to the search for earth-like planets located in the "habitable zone", because it is on them that there is a chance to find a different life.

When searching for exoplanets, two main methods are used. First, they measure how the angular velocity of a star changes under the gravitational influence of its invisible satellites. Second, they record the fluctuations in its brightness when the satellite passes against its background. Direct photographs of exoplanets can be counted on one hand, so about their physical characteristics we have to judge by indirect data, which imply a fairly wide range of options.

"Hot Jupiter" Dimidius, 51 Pegasus, as presented by the artist

Most significant impact on angular velocity and the brilliance of the star is provided by gas giant planets, therefore, for a long time, scientists have discovered only them. Because of this, the opinion even developed that giants are a typical phenomenon in the Universe, and earth-like worlds are very rare. It, for example, was expressed by Stanislav Lem. For some reason, the great Polish science fiction writer forgot about instrumental selection, which is determined by the resolution of the equipment.

The more perfect the instruments became, the more stone planets were found. First, super-earths of huge mass were discovered, and then came the turn of earth-like planets, which are only slightly larger than our world. The search began for Earth-2 - a planet that would be close to ours in mass and would be in the "habitable zone", that is, at such a distance from the star, at which there would be enough heat for existence on the surface of liquid water.

Why is it important? Because we know only one form of life - terrestrial, and it could not have arisen without liquid water, which serves as a universal solvent. Accordingly, scientists believe that the likelihood of a biosphere on a planet with water bodies is much higher than anywhere else.

Alpha Centauri system: α Centauri A, α Centauri B, Proxima Centauri. The sun is for comparison

Although Earth-like exoplanets are found in a wide variety of places, the closest worlds, of course, are of particular interest. They can become the main goal of astronautics in the future. In October 2012, the discovery of an exoplanet near Alpha Centauri B was announced. This star is the second component of a system of three luminaries, which is located at a distance of 4.3 light years from us.

The discovery made a lot of noise, but in 2015, after analyzing the accumulated data, astronomers "canceled" it. Therefore, the study of the third component - Alpha Centauri C, better known as Proxima (Nearest) - was approached with extreme caution.

The star, located at a distance of 4.22 light years from us, but not visible to the naked eye, was discovered relatively recently. In 1915 it was noticed and described by the Scottish astronomer Robert Innes; it took another two years to measure the distance to it.

Alpha Centauri C (aka Proxima), the closest star to us

Proxima is a red dwarf, and periodically flashing: its luminosity can increase sixfold at once! Research has shown that x-ray Proxima is comparable to solar, and during strong flares, which occur eight times a year, it can increase by three to four orders of magnitude. All this makes the existence of inhabited planets in the immediate vicinity of Proxima problematic, but science fiction writers have always believed that they are there.

For example, Proxima is described as the target of "ships of generations" in Robert Heinlein's Stepsons of the Universe (1963) and Harry Harrison's The Captive Universe (1969). In the story of Murray Leinster "Proxima Centauri" (1935), one of the two planets in the Proxima system is inhabited by predatory plants that are not averse to feasting on earthly astronauts. In Stanislav Lem's "Magellanic Cloud" (1955), earthlings find there two rocky planets and an ancient dead "Atlantis" starship. In Vladimir Savchenko's novel "Beyond the Pass" (1984), Proxima has desert planets on which intelligent crystalline life has developed. In the novel by Vladimir Mikhanovsky "Steps to Infinity" (1973), there is only one planet in the vicinity of Proxima, Ruton, which does not have a biosphere, but is rich in minerals.

Scientists, like science fiction writers, were interested in finding planets near the nearest star. In 1998, the Hubble Orbiting Telescope detected a suspicious object at a distance of 0.5 AU. from Proxima, however, closer observation did not confirm the discovery. Further research ruled out the possibility of the existence of brown dwarfs and gas giants in its orbits, then super-earths.

In 2013, astronomer Mikko Tuomi, studying data from long-term observations of Proxima, noticed a recurring anomaly and suggested that this indicates the presence of a small rocky exoplanet in orbit very close to the star. For verification, specialists from the European Southern Observatory, located in Chile, launched the Red Dot project in January 2016, and on August 24, the discovery of the world, which has so far been codenamed Proxima Centauri b, was officially announced.

The exoplanet turned out to be relatively small: its mass is estimated at 1.27 Earths. It rotates so close to its star (0.05 AU) that the year on it is a little more than 11 Earth days, however, due to the low luminosity of Proxima, the conditions there are quite conducive to the emergence and development of life: there is an opinion that a new the planet fits better than Mars.

Proxima b (in the artist's view) versus Earth

However, there are also problems. Due to its proximity to its luminary, the rotation of the exoplanet around its own axis must be synchronized with its revolution around Proxima, that is, it is always turned with one side to the star. It must be very hot in this hemisphere, very cold in the other. Astrobiologists say that in this case, hypothetical bodies of water and life forms should be located in the transition zone between the hemispheres. At the same time, climatic parameters can vary over a fairly wide range: they depend on the density and composition of the atmosphere, as well as on what water reserves were on the planet after its formation.

Another problem is the radiation of Proxima, because the discovered planet, even in a "quiet" time, receives from it 30 times more ultraviolet radiation than the Earth from the Sun, and X-rays - 250 times more. And if we also remember about periodic flares and superflares, then the situation for local life forms becomes completely unfavorable. Nevertheless, astrobiologists believe that the biosphere can adapt to such harsh conditions: from the deadly rays, local creatures can hide in caves or under water.

In addition, there are life forms on Earth (for example, coral polyps), who have learned to re-emit the energy of the Sun through biofluorescence. If the inhabitants of the exoplanet also mastered this technique, then they can be detected by radiation at certain wavelengths, which scientists are going to do in the future.

Alien Worlds: Aurelia (2005) explains what life might look like on an exoplanet like Proxima Centauri b.

Another discovery, which was reported on August 27, was made with the Russian radio telescope RATAN-600, which is located in Karachay-Cherkessia. Scientists working on it have caught a powerful point signal coming from the sun-like star HD 164595 - it is located in the constellation Hercules at a distance of 94.4 light years from us. By the way, a year earlier, a huge planet was discovered there with a mass sixteen times the earth's. The repetition of the signal has not yet been recorded, so astronomers avoid talking about its probable artificial origin.

In addition, calculations show that it would take a whopping 50 trillion watts of energy to generate such a signal, if it were pointed exactly at the Earth. This is more than all the energy generated by our civilization today, so the version of accidental interception of radio emission from some natural source looks the most plausible. In fact, the story is repeating itself with the signal "Wow!", Which was received in 1977 and the mystery of which has not yet been solved.

RATAN-600 telescope

Perhaps science has come close to detecting alien life. Have we got a chance for the first contact? Or will our hopes again, like half a century ago, turn into disappointment? ..

One can lose count of how many times we have heard the phrase that "scientists have found the first truly earth-like exoplanet." To date, astronomers have been able to determine the presence of more than 2,000 different exoplanets, so it is not surprising that among them there are those that, to one degree or another, are really similar to Earth. However, how many of these Earth-like exoplanets are actually habitable?

Similar statements were made in due time regarding Tau Ceti e and Kepler 186f, who were also baptized as twins of the Earth. Nevertheless, these exoplanets do not stand out in anything remarkable and do not at all look like Earth, as we would like it to be.

One way to determine how habitable a planet can be is through the so-called Earth Similarity Index (ESI). This indicator is calculated based on the data of the radius of the exoplanet, its density, surface temperature and data on the parabolic speed - the minimum speed that must be given to an object in order for it to overcome the gravitational attraction of a particular celestial body... The Earth-Similarity Index ranges from 0 to 1, and any planet with an index higher than 0.8 can be considered "Earth-like". In our solar system, for example, Mars has an ESI index of 0.64 (the same index for the exoplanet Kepler 186f), while the Venus index is 0.78 (the same index for Tau Ceti e).

Below are five planets that best fit the description of the Earth's twin based on their ESI scores.

Exoplanet Kepler 438b has the highest ESI index among all exoplanets currently known. It is 0.88. Discovered in 2015, this planet orbits a red dwarf star (much smaller and colder than our Sun) and has a radius just 12 percent larger than Earth's. The star itself is located about 470 light years from Earth. The planet makes a complete revolution in 35 days. It is in the habitable zone - the space within its system where it is neither too hot nor too cold to maintain the presence of liquid water on the planet's surface.

As with other discovered exoplanets orbiting small stars, the mass of this exoplanet has not been studied. However, if this planet has a rocky surface, then its mass may be only 1.4 times larger than the Earth's, and the surface temperature will vary from 0 to 60 degrees Celsius. Be that as it may, the ESI index is not the ultimate method for determining the habitability of planets. Scientists recently observed and found that the planet's home star Kepler 438b has very powerful emissions of radiation on a fairly regular basis, which could ultimately make this planet completely uninhabitable.

The ESI of the planet Gliese 667Cc is 0.85. The planet was discovered in 2011. It orbits the red dwarf Gliese 667 in a triple star system "only" 24 light years from Earth. The exoplanet was discovered by measuring the radial velocity, as a result of which scientists found out that in the motion of the star there are some fluctuations caused by the gravitational effect of the planet located near it.

The approximate mass of the exoplanet is 3.8 times more mass Earth, however, scientists have no idea how big the Gliese 667Cc is. It is not possible to find out this because the planet does not pass in front of the star, which would allow us to calculate its radius. The orbital period of Gliese 667Cc is 28 days. It is located in the habitable zone of its cool star, which in turn suggests that the temperature on its surface is about 5 degrees Celsius.

Kepler 442b

The planet Kepler 442b with a radius of 1.3 times the radius of the Earth and an ESI index of 0.84 was discovered in 2015. It orbits a star that is colder than the Sun and is about 1,100 light years away. Its orbital period is 112 days, which suggests that it is in the habitable zone of its star. However, the temperature on the planet's surface can drop to -40 degrees Celsius. For comparison: the temperature at the poles of Mars in winter can drop to -125 degrees. Again, the mass of this exoplanet is unknown. But if it has a rocky surface, then its mass can be 2.3 times the mass of the Earth.

The two planets with ESI indices of 0.83 and 0.67, respectively, were discovered by the Kepler space telescope in 2013, when they passed opposite their home star. The star itself is located about 1200 light years from us and somewhat colder than the Sun. With planetary radii 1.6 and 1.4 times the Earth's, their orbital periods are 122 and 267 days, respectively, which suggests that both are in the habitable zone.

Like most other planets discovered by the Kepler telescope, the mass of these exoplanets remains unknown, but scientists suggest that in both cases it is about 30 times larger than Earth. The temperature of each of the planets can support the presence of water in liquid form. True, everything will depend on the composition of the atmosphere that they possess.

Kepler 452b with ESI 0.84 was discovered in 2015 and became the first discovered potentially Earth-like planet in the habitable zone and orbiting a star similar to our Sun. The radius of the planet is about 1.6 times the radius of the Earth. The planet makes a complete revolution around its home star, which is about 1400 light years from us, in 385 days. Since the star is too far away, and its light is not too bright, scientists cannot measure the gravitational effect of Kepler 452b and, as a result, figure out the mass of the planet. There is only an assumption according to which the mass of the exoplanet is about 5 times the mass of the Earth. At the same time, the temperature on its surface, according to rough estimates, can vary from -20 to +10 degrees Celsius.

It follows from all this that even the most Earth-like planets, depending on the activity of their native stars, which can be very different from that of the sun, may not be able to support life. Other planets, in turn, have extremely different sizes and surface temperatures from Earth. However, given the increased cost last years activity in the search for new exoplanets, one cannot exclude the possibility that among those found we will nevertheless meet a planet with a mass, size, orbit similar to the Earth, and a sun-like star around which it revolves.

It is not yet clear whether the new exoplanet has an atmosphere. Because Proxima Centauri is a relatively active star, Proxima b receives X-rays 400 times what we have on Earth, and this could cause the atmosphere to evaporate away.

But Ansgar Rainers of the University of Göttingen in Germany says it all depends on how and when the exoplanet formed. Perhaps it formed farther away, where water was present, and then migrated closer to its star, or it formed initially close to Proxima Centauri. In the first scenario, the presence of an atmosphere will be more likely.

“There are many models and simulations that produce a wide variety of results, including possible atmosphere and water,” says Rainers. "We don't have the slightest idea yet, but the atmosphere is definitely possible." This would be a strong argument for the possible existence of life on the planet. And the relative proximity to our solar system makes robotic exploration possible within a generation.

“Proxima has a lifetime of several trillion years, nearly a thousand times the Sun's remaining lifetime,” says Avi Loeb of Harvard University, who heads the advisory. "The potentially inhabited solid planet near Proxima will be the first place our civilization can go after the Sun dies in five billion years."

The Starshot Initiative, which we talked about in April, is a $ 100 million program to find and explore the possibilities of interstellar travel. The first stage includes the construction of light self-propelled "nano-devices", which will be able to move at a speed of 20% light. Such a spacecraft will reach Alpha Centauri 20 years after launch. At present, the scientists of the project are trying to demonstrate the possibility of using powerful laser beams, with the help of which a light sail will move.

The discovery of a potentially habitable planet near Proxima Centauri is an excellent target for the mission, Loeb said. A spacecraft equipped with a camera and various filters will be able to take color images of the planet and determine if it is green (meaning it has life), blue (with oceans on its surface), or just brown (dry rock). The desire to learn more about the planet - namely whether there is life on it - will give Starshot a sense of rush to gather facts about the planet. In particular, those that cannot be reached using the current generation of terrestrial telescopes on Earth.

“We definitely hope we can launch these nanoprobes within a generation,” Peter Warden of the Breakthrough Prize Foundation said during a recent press conference. - Perhaps by 2060. We now know that there is at least one interesting target within the reach of our proposed system. We will be able to take pictures and find out if life exists there, possibly advanced. These are big questions, and we will get answers to them already in this century. "

The importance of discovering a terrestrial planet so close to Earth is that we can learn more about it, literally touch it, very, very soon. This may be the find of the century, because already in this century we will "visit" it.

While working with the high-precision spectrograph HARPS, installed at the Southern European Observatory (ESO), the research team discovered a small exoplanet orbiting the red dwarf Ross 128. Astronomers believe that its size and surface temperature are very close to Earth's. Even more interesting, the planet Ross 128 b is located only 11 light years from Solar system, making it the second closest exoplanet to us after Proxima b.

A quiet star and a promising planet

“This discovery was made possible by a decade of monitoring HARPS (High Accuracy Radial velocity Planet Searcher) data, along with the most modern methods analysis of information, ”says Nicola Astudillo-Defroux of the University of Geneva, co-author of the article on the new discovery. “Until now, only HARPS has demonstrated such accuracy of measurements, and for 15 years it has remained the best planet hunter in the world,” he assures.

The team notes that most red dwarfs experience intense solar flares, which usually literally blow away the atmosphere from planets and irradiate them with solar radiation. Ross 128, however, is an unexpectedly "quiet" star that does not exhibit such activity. As a result, its planets may turn out to be the closest point to our planet for colonization of other star systems. This is the special importance of the discovery: if, in the case of the well-known Proxima b, an aggressive star could destroy the planet's atmosphere and turn it into a rocky desert, then Ross 128 b gives humanity hope for space expansion.

Opening value

The orbit of Ross 128 b is 20 times closer to the star than the distance between the Earth and the Sun, but the planet receives only 1.38 times more solar radiation. As a result, the temperature on its surface does not differ much from our planet: in the coldest points it does not fall below -60 ° C, and in the hottest points it does not rise above 20 ° C. However, scientists are not yet sure whether the planet is included in this called " Goldilocks zone»- the area around the star, the conditions of which allow water on the planets to exist in a liquid state.

“Thanks to powerful modern telescopes, in 10 years we will be able to see the new planet and characterize its atmosphere. At present, we only have theoretical models, and therefore we cannot say with certainty whether liquid water exists on the Ross 128 b surface, ”Nicola explains in an interview with Futurism.

The science

Scientists have discovered a mysterious planet outside our solar system, which is most similar in size and composition to Earth, but on it too hot to maintain life.

The exoplanet was named Kepler-78b... Its orbit has puzzled astronomers - it is 20% wider, and the mass is 80% more than Earth, despite the fact that its density is the same as that of our planet.

The exoplanet is approximately 1.5 million kilometers from the star... Kepler-78b orbits its star in about 8.5 hours. The temperature on the planet is approximately 2,000 degrees Celsius, according to scientists.

The discovery was mentioned in two studies (the first and the second), the results of which were in turn published in the journal Nature.

Thanks to Kepler telescope astronomers have learned about thousands of exoplanets in our galaxy, many of them are the same size as our planet. These planets revolve around stars such as our Sun.

Despite the fact that the size of an exoplanet is easy to measure, it turned out to be quite difficult to find out its mass... Mass is an important parameter, since it allows you to find out the density of a planet, and therefore find out what this planet is made of.

Terrestrial exoplanets

Kepler-78b is very interesting because this smallest exoplanet, from which scientists were able to find out the radius and mass with great accuracy.

By astronomical standards, this planet can be called the virtual twin of the Earth.

Scientists learn the size of an exoplanet, as well as the time it will orbit its star, by measuring the amount of light that the planet blocks when it passes in front of the star.

After scientists measured the brightness of the planet Kepler-78b for 4 years, at intervals of 30 minutes, the scientists found that the brightness of the star fell by .02% every 8.5 hours as the planet flew in front of its star.

Secret planet

The planet Kepler-78b was discovered in September 2013, when it orbited a star similar to our Sun in the constellation Cygnus, about 400 light-years from Earth.

Since its launch (March 2009), the Kepler Space Telescope has been able to detect nearly 3,600 potential exoplanets.

Two teams of scientists studied mass and density new planet... Andrew Howard's team of University of Hawaii, calculated that the mass of the planet Kepler-78b is 1.69 times that of the Earth, while the data of the team of Francesco Pepe from University of Geneva showed that the exoplanet has a mass 1.86 times more.

The density that the first team calculated is 5.57 grams per cubic centimeter, while the second team's density came out at 5.3 grams per cubic centimeter.

Since each team recognizes certain inaccuracies, it can be said with confidence that scientists are right in their calculations... It is worth noting that the Earth's density is 5.5 grams per cubic centimeter. This means that the new exoplanet may have the same composition as Earth.

New planet

The new planet revolves around its sun, gradually approaching it, and, approximately in 3 billion years her days will be numbered- the colossal gravity of the star will tear it to pieces.

Astronomically, the planet will become part of a star very soon. On Kepler-78b it will not be possible find alien life, due to too high temperature on its surface.

And yet, the mass and density of the new planet, similar to that of Earth, allows us to hope that somewhere there is a twin planet of our Earth, which has a similar size, composition and temperature on its surface.

According to Drake Deming of University of Maryland, the existence of Kepler-78b, proves that, outside our solar system, planets similar in composition to Earth are not uncommon.

Deming hints at a new NASA program called TESS (Transiting Exoplanet Survey Satellite)... This will be the space telescope currently being developed by Massachusetts Institute of Technology... Within two years, his mission will be to find and study of unknown transiting exoplanets revolving around bright stars.

* Our planet has no constant weight. According to scientists, every year the Earth becomes heavier by 40,000 -160,000 tons, but manages to drop about 96,600 tons, which means a loss of about 56,440 tons.