Scientists may have Discovered Planets more Suitable for Life Than the Earth

 

Outside the solar system, there are at least more than twenty planets that may be more suitable for life than the earth. The researchers wrote in the September 18th issue of Astrobiology that these planets are slightly older, wetter, warmer, and slightly larger than the Earth. All these factors may mean that some of these planets will be the best destinations for finding extraterrestrial life. This rendering shows the first confirmed Earth-sized planet orbiting a distant star within a habitable range. This rendering shows the first confirmed Earth-sized planet orbiting a distant star within a habitable range "We must focus on some of the planets that are most likely to breed complex life. But at the same time, we should also be vigilant and not be too persistent in searching for a second earth, because there may be planets that are more suitable for life than the earth," the Celestial Body of Washington University Biologist Dirk Schultz-Marcucci said. In search of super habitable planets So far, astronomers have discovered more than 4,000 extrasolar planets. Most of these planets are not habitable. For example, the planet KELT-9b is very hot and its atmosphere is constantly melting. The darkest known planet TrES-2b has an atmospheric temperature of 1,800 degrees Fahrenheit (900 degrees Celsius). The uninhabitable planet GJ 433 d is extremely cold. Its discoverer said that this is the coldest Neptune-like planet ever discovered. However, there are also many planets and their stars within the "habitable range", or the distance between them and the stars is "just right", and can maintain the surface temperature suitable for life evolution, neither too cold nor too hot. Schultz-Marcucci and his colleagues intend to discover the most likely "super-habitable" exoplanets. In other words, in addition to being within the habitable range, they also have other characteristics that make them a good place for life to multiply.

These features include a star of the right size and the right life span, especially considering that on our planet, the evolution of complex life took 3.5 billion years, and the emergence of humans took another 4 billion years. The researchers wrote that the larger the planet, the larger the land mass and habitat space; a larger planet will have a greater gravity and therefore a thicker atmosphere, which is more conducive to the survival of flying creatures. Considering that there is no large area of ​​barren polar regions, planets slightly warmer than the earth will be more habitable, but planets warmer than the earth must be wetter than the earth, otherwise there will be deserts everywhere. Therefore, a more habitable planet may resemble the Earth in the early Carboniferous 395 million years ago when many land masses on Earth were in tropical rain forest climate. (Modern global warming is not conducive to the survival of life on the earth, not only because the change is too fast, many animals cannot adapt; also because the rise in sea level will affect the infrastructure for human existence; however, a slightly higher temperature is essentially It is harmless to life.) The researchers also wrote that the upgraded version of the Earth may also "bend" a larger moon, or a slightly closer moon, which will help stabilize the planet’s orbit and prevent life-disturbing Tremor.

The researchers then gave a set of parameters to determine whether the candidate planet meets all these criteria. Based on these parameters, the Fengyun complete beauty of super-habitable planets will be around a K-type main sequence star running (K-type main sequence star is a relatively little stars than our sun slightly lower temperature, so it Called orange dwarfs); aged between 5 billion and 8 billion years; 10% larger than the earth; average temperature is 9 degrees Fahrenheit (5 degrees Celsius) higher than the earth; the surface is humid, the land and water are scattered, and the atmosphere contains oxygen The amount is between 25% and 30%. This perfect planet will also have a plate structure or a geological process similar to the earth, which can circulate minerals and nutrients through the crust and create diverse habitats and topography. And, it also has a moon whose size is between 1% and 10% of its own size, which rotates around it at an appropriate distance.

Looking for life. Of course, it is not realistic to evaluate a distant exoplanet according to all these criteria. For example, we cannot calculate the area of ​​land masses on exoplanets, let alone the distribution of land masses. But based on some measurable factors (such as star type and planetary radius, etc.), the researchers studied some celestial bodies that may meet the above criteria and have been observed by the Kepler telescope. Subsequently, they found 24 "interesting Kepler objects", but these objects are not necessarily all planets. Among the 24 "Kepler objects of interest", two have been confirmed as exoplanets (Kepler 1126 b and Kepler-69c). Some may be false positives, but they are not actually planets. Of these 24 celestial bodies, 9 orbit the appropriate type of star, 16 are within the appropriate age range, and 5 are within the appropriate temperature range. Only one KOI 5715.01 meets the above three conditions at the same time. However, the researchers write that the true surface temperature of the planet depends on the intensity of the greenhouse effect in its atmosphere.

These 24 possible planets are all 100 light-years away from us. Moreover, even with the most powerful telescopes we currently have, some planets are too far away to study temporarily. For example, the planet Kepler-69c is more than 2,000 light-years away, which means that it will be difficult for astronomers to observe it closely for signs of life for a long time. However, Schultz-Marcucci and his colleagues write that it is important to find out what makes a planet a "super-habitable planet" because it is not impossible to find such a planet within 100 light-years. If such a planet can be found, it should be the first destination for us on earth to find extraterrestrial life in the universe.