With the help of telescopes of the European Southern Observatory (ESO), astronomers have managed to make another amazing discovery. This time they have found clear evidence of the existence of an exoplanet orbiting the closest star to Earth - Proxima Centauri. The world, called Proxima Centauri b (Proxima Centauri b), has long been sought by scientists all over the Earth. Now, thanks to his discovery, it has been established that the period of his revolution around his native star (year) is 11 Earth days, and the surface temperature of this exoplanet is suitable for the possibility of finding water in liquid form. By itself, this stone world is slightly larger than the Earth and, like the star, has become the closest to us of all such space objects. In addition, it is not just the closest exoplanet to Earth, it is also the closest world suitable for the existence of life.
Proxima Centauri is a red dwarf, and it is located at a distance of 4.25 light years from us. The star got its name for a reason - this is another confirmation of its proximity to the Earth, since proxima is translated from Latin as “nearest”. This star is located in the constellation of Centaurus, and its luminosity is so weak that it is completely impossible to see with the naked eye, and besides, it is quite close to the much brighter pair of stars α Centauri AB.
During the first half of 2016, Proxima Centauri was regularly observed using the HARPS spectrograph installed on the 3.6-meter telescope in Chile, as well as simultaneously by other telescopes from around the world. The star was studied as part of the Pale Red Dot campaign (a pale red dot or red speck), during which scientists from the University of London studied the oscillations of a star caused by the presence of an unidentified exoplanet in its orbit. The name of this program is a direct reference to the famous image of the Earth from the far reaches of the solar system. Then Carl Sagan called this picture (blue speck). Since Proxima Centauri is a red dwarf, the name of the program has been adjusted.
Since this topic of exoplanet search has generated widespread public interest, scientists' progress in this work from mid-January to April 2016 was constantly publicly published on the program's own website and through social media. These reports were accompanied by numerous articles written by experts from all over the world.
“We received the first hints of the possibility of the existence of an exoplanet here, but our data then turned out to be inconclusive. Since then we have been working hard to improve our observations with the help of the European Observatory and other organizations. For example, the planning of this campaign took approximately two years,” Guillem Anglada-Escude, head of the research team.
Data from the Pale Red Dot campaign, combined with earlier observations from ESO's observatories and others, showed a clear signal of the exoplanet's presence. It has been very accurately established that from time to time Proxima Centauri approaches the Earth at a speed of 5 kilometers per hour, which is equal to the usual human speed, and then moves away at the same speed. This regular cycle of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting Doppler shifts indicated the presence of a planet here with a mass of at least 1.3 times the mass of the Earth at a distance of 7 million kilometers from Proxima Centauri, which is only 5 percent of the distance from Earth to the Sun. In general, such a detection has become technically possible only in the last 10 years. But, in fact, even signals with smaller amplitudes have been detected earlier. However, stars are not smooth balls of gas, and Proxima Centauri is a very active star. Therefore, accurately detecting Proxima Centauri b became possible only after obtaining a detailed description of how the star changes on time scales from minutes to decades, and monitoring its luminosity with light-measuring telescopes.
“We continued to check the data so that the received signal did not contradict what we found. This was done every day for another 60 days. After the first ten days, we had confidence, after 20 days we realized that our signal was in line with expectations, and after 30 days all the data categorically stated the discovery of the exoplanet Proxima Centauri b, so we began to prepare articles on this event.
Red dwarfs, such as Proxima Centauri, are active stars and have many tricks in their arsenal to be able to mimic the presence of an exoplanet in their orbits. To eliminate this error, the researchers monitored the change in the brightness of the star using the ASH2 telescope at the San Pedro de Atacami Observatory in Chile and the Las Cumbres Observatory telescope network. Information about radial velocities as the star's luminosity increased was excluded from the final analysis.
Despite the fact that Proxima Centauri b rotates much closer to its star than Mercury orbits the Sun, Proxima Centauri itself is much weaker than our star. As a result, the discovered exoplanet is located exactly in the region around the star, suitable for the existence of life as we know it, and the estimated temperature of its surface allows the presence of water in liquid form. Despite such a moderate orbit, the conditions of existence on its surface can be very strongly influenced by ultraviolet radiation and X-ray flares from the star, which are much more intense than the effects that the Sun has on Earth.
The actual possibility of this kind of planet supporting liquid water and having life like Earth is a matter of intense but mostly theoretical debate. The main arguments that speak against the presence of life are related to the proximity of Proxima Centauri. For example, on Proxima Centauri b, such conditions can be created under which it always faces the star on one side, which is why there is eternal night on one half and eternal day on the other. The planet's atmosphere could also slowly evaporate or have more complex chemistry than Earth's due to strong ultraviolet and X-ray radiation, especially during the star's first billion years of life. However, so far, no argument has been definitively proven, and it is unlikely that they will be eliminated without direct observational evidence and obtaining accurate characteristics of the planet's atmosphere.
Two separate papers were devoted to the habitability of Proxima Centauri b and its climate. It has been established that today the existence of liquid water on the planet cannot be ruled out, and in this case it can be present on the surface of the planet only in the sunniest regions, either in the hemisphere of the planet, always facing the star (synchronous rotation), or in the tropical zone (3: 2 resonant rotation). The rapid movement of Proxima Centauri b around the star, the strong radiation of Proxima Centauri and the history of the formation of the planet made the climate on it completely different from that on Earth, and it is unlikely that Proxima Centauri b has seasons at all.
One way or another, this discovery will be the beginning of large-scale further observations, both with current instruments and with the next generation of giant telescopes, such as the European Extremely Large Telescope (E-ELT). In the coming years, Proxima Centauri b will become a prime target for the search for life elsewhere in the universe. This is quite symbolic, since the Alpha Centauri system is also chosen as the target of humanity's first attempt to move to another star system. The Breakthrough Starshot project is a research and engineering project within the Breakthrough Initiatives program to develop a concept for a fleet of light sail spacecraft called the StarChip. This type of spacecraft would be able to travel to the Alpha Centauri star system, 4.37 light-years from Earth, at between 20 and 15 percent of the speed of light, which would take 20 to 30 years, respectively, and about 4 more years to notify the Earth of a successful arrival.
In conclusion, I would like to note that many accurate methods for searching for exoplanets are based on the analysis of its passage through the disk of a star and starlight through its atmosphere. There is currently no evidence that Proxima Centauri b passes through the disk of its parent star, and the chances of seeing this event are currently negligible. However, scientists hope that in the future the efficiency of observational instruments will increase.
Artist's view of the surface of Proxima Centauri b
Computer simulations have shown that the conditions on Proxima Centauri b can be suitable for the existence of life if the planet has an atmosphere similar in density to Earth's. In this case, the gaseous shell of the exoplanet will be able to protect its inhabitants from the harmful effects of radiation from the central star. Article published in the journal Monthly Notices of the Royal Astronomical Society: Letters.
The planet Proxima Centauri b astronomers this year and immediately aroused great interest from the scientific community. This is not surprising: firstly, it revolves around the nearest star to the Earth - Proxima Centauri, and secondly, it is located in a potentially habitable zone, that is, where liquid water can exist. However, observational data that would make it possible to reliably judge whether life can exist on Proxima b are still insufficient. In fact, all that is known to scientists is the period of rotation of the planet (11.2 Earth days), the approximate mass (1.2 Earth masses) and the distance from the star (0.05 astronomical units). Nevertheless, based on this information, as well as information about Proxima Centauri, it is possible to build models, albeit based on various assumptions.
Thus, calculations show that a large amount of extreme ultraviolet and X-ray radiation will fall on the surface of the planet. Researchers estimate that Proxima b should receive at least 250 times more X-ray radiation than the Earth. This imposes certain restrictions on the possibility of the existence of life on the planet, since X-rays are ionizing, that is, harmful to living organisms. Thus, the lethal dose of radiation for humans is 5 to 10 sieverts, for goldfish - 100 sieverts, 100-1000 sieverts for insects, 10,000 sieverts for viruses and 10,000 - 100,000 sieverts for bacteria. Deinococcus radiodurans.
However, the author of the new work, Dimitra Atri, believes that life on Proxima b can exist even if flares and coronal mass ejections occur on Proxima Centauri, accompanied by bursts of high-energy protons. He came to this conclusion by evaluating the probable size of stellar flares (based on registered solar flares), the possible density of the planet's atmosphere and the magnetic field strength.
The dose of radiation that will reach Proxima b as a result of a flare at Proxima Centauri if the atmosphere has a "column density" of 100 (solid line), 300 (dotted line), 700 (short dashes) and 1000 (long dashes) grams per centimeter in square. The horizontal line shows the average daily dose of radiation from the natural radiation background on Earth.
The astrophysicist's calculations showed that if the planet has a gaseous shell that is not inferior in density to the earth's ("column density" is about 1000 grams per centimeter squared) and the same magnetic field as that of the Earth, then organisms on its surface will be able to survive most outbreaks on Proxima Centauri. According to the researcher, even powerful flares with an energy of more than 1×10 35 erg are unlikely to harm the planet's biosphere (large flares on the Sun have an energy of about 1×10 32 erg). In the event that the atmosphere becomes less dense (a "column density" of 700 grams per centimeter squared), high-energy particle emissions will become a threat to some species, such as humans. In the worst case, if Proxima b has almost no magnetic field, flashes will “blow away” the atmosphere from it and then all life like Earth will die.
Nevertheless, the author of the work emphasizes that when assessing the viability of the planet, it is necessary to take into account not only the one-time, but also the cumulative effect created by bursts of high-energy protons. On red dwarfs of the spectral class M (which include Proxima Centauri), flares with a power of 10 34 -10 35 erg occur approximately once a decade, and with a power of 10 32 - every five days. A relatively small dose of radiation (about 0.01 sievert) will still fall on the surface of a planet with an atmosphere and a magnetic field strength like that of the Earth, but with deviations - for example, with a thinner atmosphere - they will already harm living organisms (for example, For a person, a dose of radiation from 50 millisieverts is considered harmful).
Recently, astrophysicists have tried to calculate the possible composition and structure of Proxima b. According to their estimates, there is an ocean on the surface of the planet, but these calculations are very approximate. Models by other researchers show that Earth-like planets may well form around dim stars, and scientists also assume the existence of oceans on them.
Kristina Ulasovich
After several years of studying Proxima Centauri, astronomers have finally found evidence that this star has a planet, and very similar to Earth: only slightly larger. In addition, the orbit of the planet is located in the habitable zone of the star, that is, liquid water can exist on its surface.
The modern public is no longer surprised by reports of the discovery of exoplanets. Thanks to the advent of effective detection methods and vehicles such as the Kepler space telescope, the number of recorded escoplanets is in the thousands. Of interest are the discoveries of terrestrial exoplanets and exoplanets in star systems located near the solar system. The current news, reported by the European Southern Observatory, satisfies both conditions at once. The new Earth-like planet is so close to Earth that there is nowhere closer.
The found planet was named Proxima b. It revolves around Proxima Centauri - a red dwarf, one of the three components of Alpha Centauri. The distance to the Earth from Proxima Centauri is 4.25 light years, there are no stars that would be even closer. The last record for planets where life is possible was 11.7 light years. It belonged to the planet Wolf 1061c in the constellation of Ophiuchus.
The discovery was first reported by journalists from the German weekly Der Spiegel in early August, citing an anonymous source. Astronomers were in no hurry to confirm this news. However, earlier this week, the European Southern Observatory announced, and held a press conference on August 24, where scientists shared details about Proxima b. Also, the results of their work are reflected in an article published in the journal Nature.
Scientists have been observing Proxima Centauri using the High Accuracy Radial velocity Planet Searcher (HARPS) installed at the La Silla Observatory in Chile on a 3.6-meter telescope of the device. In 2012, with its help, they discovered a planet that revolves around another component of the triple star - Alpha Centauri B, however, now the existence of this planet has been called into question.
To detect exoplanets, HARPS uses a spectrometric measurement of the radial velocity of stars ("Doppler method"). It allows you to fix signs of the movement of a star. Since, if a star has a planet or several planets, they rotate around a common center of mass, then the movements of the star allow us to calculate the planet invisible to us. Usually, for this effect to be noticeable, the star must have several planets or one, but very large planet (for example, the so-called "Super-Jupiter"). If we are talking about terrestrial planets, then their influence on the position of the star will be insignificant. The common center of mass of the star-planet system in this case is likely to be inside the star, so it will only make small oscillations. But the proximity of Proxima Centauri to Earth made it possible to track them too.
Scientists have observed signs of the planet Proxima b for 60 consecutive nights since January 2016. According to their calculations, the mass of this planet is only 1.3 times the mass of the Earth, and it revolves around its star with a period of 11.2 days. Proxima b is located very close to the star, at a distance of only 5% of the distance from the Earth to the Sun. But there is a chance that the surface of this planet still does not look like a hot desert. The fact is that Proxima Centauri is not a very bright star. According to calculations, Proxima b receives only 65% of the energy that the Earth receives from the Sun. So liquid water can indeed exist on its surface. “There is a reasonable suspicion that this planet may be able to become a receptacle for life,” says one of the authors of the discovery, Guillem Anglada-Escudé of Queen Mary University in London.
But all the same, it is unlikely that conditions on Proxima b are particularly favorable for life. The force of gravity most likely oriented it so that one hemisphere always looks at Proxima Centauri, and the second - in the opposite direction, similar to how the Moon is turned in relation to the Earth. As a result of this, on one half of the planet there is a constant day, and on the other it is night, and the temperature difference between them is huge. While approximate calculations show that the average temperature on Proxima b should be -40 ° C, but if it has an atmosphere, then this figure will be higher. For comparison, on Earth without an atmosphere and oceans, the average surface temperature would be between -20°C and -30°C.
Due to its proximity to Proxima Centauri, the planet receives 100 times more high-energy radiation (in the ultraviolet and X-ray range) than the Earth. This factor is also not conducive to the presence of life. The situation is also complicated by the fact that Prxima Centauri is a flaring variable star, and during flares its luminosity can increase several times. A magnetic field can serve as protection against high-energy particles, but we do not know if the planet Proxima b has it.
In addition to discussions about the possibility of water and life on Proxima b, which still seem somewhat premature, other mysteries are connected with the new planet. For example, the very formation of a rocky planet at such a small distance from a star seems unlikely. According to the assumption made by Guillem Anglada-Esküde, Proxima b could have formed elsewhere, further from the star, and then, for reasons that are still unclear, move to a closer orbit. If so, then the presence of water on the planet becomes more likely.
Now astronomers have begun to try to fix the passages of Proxima b against the background of the stellar disk of Proxima Centauri. Observation of such passages will allow them to more accurately determine the size and mass of the planet, and therefore calculate its density, testing the hypothesis that it is a rocky rather than a gas planet. Starlight passing through the atmosphere of Proxima b will allow scientists to find out what gases are included in its composition. But the chances of observing such passages in the conditions of Proxima Centauri are small. Therefore, the main hope is placed on the James Webb and TESS (Transiting Exoplanet Survey Satellite) space telescopes, which are still planning to launch.
In August 2016, the staff of the European Southern Observatory announced an amazing discovery. It turned out that an unusual exoplanet, Proxima Centauri b, rotates around Proxima Centauri, the nearest star just 4.25 light years away from us, with a period of 11.2 Earth days. Its main feature is that the probability of having life on it is extremely high, although the conditions in which Proxima Centauri b is located are not at all the same as in the solar system. And if so, the story of this far-close planet is directly related to our beloved biology.
In general, we are serious people. The granite of science crunches on our teeth. We cover such harsh, such complex nooks and crannies of biological knowledge, which the lanterns of other popular science sites have not reached. But sometimes we just want to fool around. And to talk about science in a cheerful language, to show it from a different angle. Draw funny pictures, write light and funny text. That is why we have opened a new section - "12 biological news in pictures".
The intellectual partner of these illustrated stories is JSC RVC.
Information about the existence of Proxima Centauri b (shortly - just Proxima b) was leaked to the network on August 12, 2016. Literally two weeks after that, on August 24, employees of the European Southern Observatory confirmed the rumors about the discovery of a new planet. And several preprints of scientific articles appeared on the Internet at once, the authors of which discussed its habitability. Subsequently, a number of these articles were published in the journal Astronomy & Astrophysics .
First you need to say how the planet was discovered. Not all biologists are strong in physics, so it is all the more worth noting the method that made it possible to “see” the potential nearest habitable planet to us. It bears the name radial velocity method or Doppler method. The fact is that not only the star affects the planets belonging to it, but the planets also change the behavior of their star. The gravity of the planet slightly shifts the radial velocity of the star associated with it, as if rocking it. Changes of this kind are recorded by spectrographs, because the spectrum of the star changes.
In order for a planet to significantly influence the motion of its star, it must be quite large - have a mass no less than the earth's, but better at least several times more. So we can say for sure that Proxima b is “more chubby” than our space house. It is even known how much - 1.3 times.
What else do we know about this planet? It is known that it is 300 million years older than the Earth, which means that if life once arose there, it had more time to develop. Who knows, maybe the Proximovites are already developing vehicles capable of flying not much slower than the speed of light? Be that as it may, we cannot yet fly to test this: with our current space engines, it will take tens of thousands of years, and even then, provided that trillions of dollars are spent on the flight.
It is also known that the "host" of Proxima b, the star Proxima Centauri, is a red dwarf. The emission spectrum of stars of this type differs sharply from that of the sun. Red dwarfs put out much more ultraviolet light than yellow dwarfs like the Sun. In addition, they "spoil" their planets with X-rays. But in the case of Proxima b, this may not be so scary. The atmosphere there, apparently, is very dense, well delaying various harmful rays. Nevertheless, at the dawn of its time, the planet was hardly inhabited: then Proxima Centauri gave out a lot of ultraviolet and X-ray radiation, and only then “settled down”.
How to describe habitability?
The suitability of a planet for life is determined by several parameters:
- relatively small size and mass (about the same as that of the Earth);
- the temperature is at least in places above zero Celsius, but not much;
- the presence of liquid water;
- the absence of hard types of radiation that can damage DNA and other biological molecules.
This is not the whole list, but, perhaps, the main criteria are listed in it. In other words, potentially habitable planets should be similar to the Earth in many ways. And no wonder: this is the only planet known to us that is definitely inhabited.
More detailed discussions about the suitability of different planets for life can be seen in the article " wild wild space”, but as for our Earth, it is best to read the book by Mikhail Nikitin“ Origin of life. From Nebula to Cell» .
Hard ultraviolet radiation plays a cruel joke on life, because it splits water molecules into hydrogen and oxygen. Hydrogen also escapes easily from planets with moderate gravity. If so, scientists should have calculated how much water Proxima b could have lost during the time its red dwarf misbehaved. Let the density of the atmosphere of this exoplanet be approximately the same as that of the Earth. Then Proxima b could lose from 0.4 to 0.9 of the volume of the earth's oceans. It seems that this is a lot, but in fact it is quite small, given that our Earth has lost a quarter, or even more, of the water of its oceans in its history. And besides, a significant part of the losses can be restored due to the water contained in the planet's mantle. If so, most likely, there is enough water on Proxima b now. Moreover, this water is liquid: the planet is 20 times closer to its star than the Earth is to the Sun, and therefore, it is quite warm there.
In October 2016, there was even a hypothesis that the ocean on Proxima b could have a depth of up to 200 kilometers,. It is based on calculations of the diameter of the planet, depending on its composition, with a known mass (recall, this is 1.3 Earth). According to the authors of the scientific article, Proxima b probably has a compact core of silicates, covered with water on top. The mass of water is almost half of the mass of the entire planet.
The most interesting thing is that such an abundance of water does not help life, but rather reduces the likelihood of its presence on Proxima b. The fact is that such a thickness of H 2 O creates too much pressure at the bottom. Under such conditions, even hot water can turn into an exotic version of ice - so unusual that it does not exist on Earth. It will absorb up to 95% of the total mass of water on the planet. But ice - it is ice: its crust will not allow the ocean to communicate with the silicate core, which means that salt will have nowhere to come from. Well, distilled water is far from the best place for the emergence and maintenance of life. Let's remember school textbook blood cells that swell and even burst under the influence of water with a minimum salt content.
On the other hand, such a harsh model of Proxima b is extreme. The ocean there may not be that deep, it all depends on the physical parameters that are “driven” into the program. Their values are yet to be confirmed experimentally.
As for the climate, the issue is complex. The planet is close to its star, which means that their mutual attraction can prevent Proxima b from rotating around its axis. As a result, the planet is probably always turned to its luminary with one side, very warm, and its other hemisphere is cold all the time. True, the difference in temperatures between the "day" and "night" sides can be significantly smoothed out by a dense atmosphere. She, most likely, is on Proxima b.
By the way, calculations published already in 2017 lowered the likelihood that the planet does not really rotate around its axis. They showed that the orbit of Proxima b is quite elongated: its eccentricity is 0.25. And this means that at least at the extreme points of its orbit, the planet is not so strongly attracted by the star. Probably, on it, as on our Mercury, a day is equal to 2/3 of its own year and in this case lasts about one Earth week. All together, this means that the difference in climate at different points on the exoplanet is not so great, so the chances of finding life there increase.
One of the most outstanding astronomers of 2016 according to the magazine Nature Guillem Anglad-Escude even fantasized about what such a life would look like. He said in an interview with a Spanish popular science publication that "proximian" plants, if any, look unusual, because in the radiation of Proxima Centauri, the infrared part of the spectrum is the most invisible to our eyes. But this red dwarf almost does not give visible light of green shades, like that of the Sun. Thus, in order to survive under its rays as efficiently as possible, plants on Proxima b would do well to have a reddish tint, and not green at all.
Not only the local flora may look unusual. The fauna of red dwarfs will also be slightly unusual. If we assume that the biosphere there has reached large multicellular organisms, then among them there will be no analogues of polar bears, arctic foxes and other hares in winter coloring. She just doesn't make sense. 95 percent of the radiation from Proxima Centauri is infrared. Snow and ice in it are “black”, that is, they absorb light well and, unlike the Earth, quickly melt even with a short day. A stable snow cover in winter under such conditions is unlikely - just like animals in a "winter" camouflage coloration.
In general, whether there is life on Proxima b or not, it is not yet possible to say with absolute certainty. But the information currently available suggests that the patient is more likely alive than dead. And if he is alive, we can theoretically see a lot of interesting things on him.
Literature
- Guillem Anglada-Escudé, Pedro J. Amado, John Barnes, Zaira M. Berdinas, R. Paul Butler, et. al. (2016). A terrestrial planet candidate in a temperate orbit around Proxima Centauri . Nature. 536 , 437-440;
- Ortega I. (2016). European scientists highly appreciated the viability of Proxima b. "Life";
- Martin Turbet, Jérémy Leconte, Franck Selsis, Emeline Bolmont, François Forget, et. al. (2016). The habitability of Proxima Centauri b. "Life";
- Ortega I. (2016). Astronomer of the Year: Planet near nearest star covered in strange vegetation. "Life"..
If you weren't on Earth on Wednesday, you missed this: astronomers have found a planet as close to us as it can possibly be in the nearest star system, Alpha Centauri. A planet called Proxima Centauri b completes a circle around its star every 11.2 days. And yes, it is in the "potentially habitable zone", the Goldilocks zone, where liquid water can (for now) be on the surface. Its mass - 1.3 Earth - implies that the planet should (so far only should) be solid. No wonder we have already listed it as one of the greatest discoveries of the century.
But wait a minute. Astronomers have found other Earth-like planets in habitable zones in recent years. According to the Planetary Habitability Laboratory at the University of Puerto Rico, 15 potentially habitable "Earth-sized" exoplanets (in terms of mass or radius) have now been confirmed. And while yes, Proxima Centauri b has a mass that is oh so close to Earth, otherwise it might not be so earthy.
What really sets this planet apart from the competition and what caught my attention in the first place is its location. In the same way that the nearest supermarket to the house will become the most visited store for you, Proxima Centauri b warms the soul of scientists with its proximity and attractiveness. However, this attractiveness is still in question.
First, scientists so far only know the minimum mass of Proxima Centauri b - the smallest mass that it can have - and do not know its radius. That is, they do not know for sure whether it is solid or not.
“Remember we only have the minimum mass of this planet,” astronomer Elizabeth Tasker tweeted. “By that measure, I would be the twin of most life forms on Earth.”
In addition, the star harbors the planet with high-energy radiation, which means it dried up all the water a long time ago. If at least some hydration remains, it will be only in the most sunlit places. While "warm enough to have water" is an important fact, it cannot be equated with actual habitability.
Rory Barnes, an astronomer at the University of Washington, has developed a habitability index that evaluates potentially pleasant planets based on a large number of nuances. And his conclusions are disappointing. "I'm pessimistic about any planet being habitable because there are too many requirements to be met," he says. "But Proxima gives us a great chance to find out if I'm right or not."
In light of all this uncertainty, the hype, or as it is fashionable to call it now - hype, about this planet seems premature or just plain wrong. But the hype is definitely there.
“I was surprised when I read an article from the European Southern Observatory, which was very clear: this is the most Earth-like planet we have found so far,” says Lisa Messery, an anthropologist at the University of Virginia, “despite the fact that in in the same article they wrote that the planet has no seasons, the year lasts 11 days, the sky should be red, and Proxima Centauri is an active star with solar flares. In other words: it is generally an uninhabited world.”
Messeri doesn't study exoplanets. She studies people who study the planets - following them and interviewing them for many years. The response to this discovery, she says, has more to do with Proxima's proximity to us. "The reason we care about this planet is because it's a place that we can go to and be." In the case of most planets, we can only imagine. But Proxima Centauri b is the first exoplanet that could become physically reachable.
Earth geography similarly influences our perception. “We feel connected to places that are close to us because we can go there on the weekend,” Messeri says. "Even if I'm not going to New York on Saturday, the fact that I can makes it part of my world."
Forward and with a song
Although scientists are not going to Alpha Centauri on Saturday, they definitely intend to fly there. The Breakthrough Starshot Initiative, which announced in April, plans to send probes the size of a postage stamp to the star. At the time of Proxima's announcement, the people behind the project had not yet decided which star in the triple system they wanted to visit (but now the choice is almost obvious).
True, it is still too early to discuss interstellar space travel - in the sense of seriously discussing it. Scientists try to stay away from such discussions. But now there is a reason and a place to point to, Messeri says. With such a place, scientists can quite honestly and passionately speak publicly about interstellar intentions.
The proximity of the new planet also makes the search for alien life more reasonable. There is a real star, a real earth-like planet, really nearby. If a Contact-style signal came from that system, you could bet a million dollars that the governments of the world would band together and send people there. Because the interstellar human travel to Proxima is the space version of Messeri's weekend trip to New York.
Sending an interstellar message to aliens instead of waiting to receive one has historically been considered a philosophical exercise. A message can take many generations to reach its destination, as can a hypothetical answer. But with Proxima, we get something like a real conversation with aliens, like meeting with a stranger, says Douglas Vakoch, head of METI International. "In less than a decade, we could send a message and get a response from interested Centauri."
The more traditional sciences will also share in the benefits: for example, the European Extremely Large Telescope will be able to take pictures of this planet, which will provide at least a little new information (maybe a lot). It will allow scientists to find possible biosignatures indicating the existence of life. Scientists go crazy at the very thought of such a possibility, because the closer the planet, the more information we can learn about it.
looking in the mirror
And yet it's not Earth's twin, no matter what the headlines say, and scientists haven't found Earth's twins yet. Hot jupiters are cool; planets with glassy rains are also fun; super-earths are generally something supernatural. Compiling a complete census of exoplanets would be a very valuable acquisition. But most scientists, according to Messeri, really just want to find another Earth. This is reflected in scientific priorities. The Kepler space telescope, which has found more planets than anyone else on this planet, was "specially designed to survey part of our region of the Milky Way galaxy in search of dozens of Earth-sized planets in or near the habitable zone," according to NASA.
The search for an "Earth twin" is a pursuit of the Platonic ideal, Messeri says. "It allows us to see the Earth in its prime as we would like to see it, one that is not ravaged by climate change, war or disease."
But we have not yet found such a place. And we may never find it. In your quest to find the perfect match, you usually find someone who is super cool but yells at you when they're hungry or hates your mom. In search of the perfect job, you find yourself in the role of a dishwasher. In this sense, the discovery of Proxima Centauri b is a representation of humanity's desire for perfection, for a pure and virgin Earth.
Most likely, this will happen all the time. We set ourselves a great goal and failed. Not because we are so unlucky, but because we were doomed to it from the very beginning, because this is the nature of humanity: to always strive for the ideal and never achieve it.
