21 light-years away, this planet is very similar to Earth, astronomers: 100% of life exists

For many years, human beings have always wanted to find a habitable planet outside the earth that can be "packed in". At the same time, they also hope to find extraterrestrial life among the more than 4,000 known exoplanets. Even the existence of alien civilizations, then, among these planets, which planet is the most reliable?

21 light-years away, aliens may be monitoring the earth!

Only 20.5 light-years away from the earth, there is a very special exoplanet named Gliese 581g (Gliese 581g), which orbits a red dwarf star. Currently, In this star system, the existence of 6 exoplanets has been confirmed, which also means that this is a rare star system with multiple planets outside the solar system.

Scientists first discovered it in 2010, and then through further exploration and research, it was finally confirmed that the planet Gliese 581g is a planet very similar to Earth, and it is still in the habitable zone. middle.

What is the basic situation of Gliese 581g? Scientists from the United States said that through years of observation and research, they believe that the mass of Gliese 581g is about 3-4 times that of the earth, and its diameter is about 1.2 times that of the earth, and its average temperature is about At about minus 12 degrees Celsius, at the same time, the orbital period is about 37 Earth days.

Although it seems that the surface temperature of Gliese 581g is very low compared to the earth, don’t forget that what we are talking about here is the average surface temperature of Gliese 581g.

You must know that the average temperature of the earth today is about 15 degrees Celsius. This is the effect of the industrial revolution, which has caused the average temperature of the earth to rise by more than 1 degree.

At the same time, on the earth, there are tropical regions with extremely high temperatures of tens of degrees, and polar regions with minus tens of degrees. Naturally, the same is true for Gliese 581g. Because of its low average temperature, it also means that even the hottest areas on the Gliese 581g may be extremely comfortable for humans, say around 10-20 degrees Celsius , Naturally, for human beings, it is a very habitable planet.

This also means that, in addition to the extremely cold regions above Gliese 581g, there is also liquid water on this earth-like rocky planet, which also makes it more interesting to study.

Researchers from the University of California in the United States believe that the possibility of life on Gliese 581g is 100%. This can be said to be a very high degree of certainty, which also means that there may not only be low-level creatures on Gliese 581g, but also alien civilizations may be found on it.

Or if Gliese 581g is old enough, then the alien civilization on it may be silently observing the earth just like scientists on earth observe it, and speculating that there may be life on earth, and even It's an alien civilization.

Speaking of which, in the star system where Gliese 581g is located, the habitable planet favored by scientists is not just Gliese 581g, the other one is closer to the earth, only about 20.3 light-years away The planet Gliese 581d is also considered to be a "super-Earth" that is likely to have life, and as early as 2015, the planetary identity of Gliese 581d has been confirmed through a large number of observational studies.

This also means that although the star Gliese 581 is just a red dwarf star, there are many habitable planets around it, just as there are many planets in the habitable zone in the solar system. .

The researchers believe that the size of Gliese 581d is larger than that of Gliese 581g, and its mass is about 6 times that of the Earth. At the same time, its average surface temperature is obviously higher than that of Gliese 581g. This also means that the top of Gliese 581d also supports the existence of liquid water, and there may even be abundant life.

Since the discovery of Gliese 581d and Gliese 581g, scientists believe that there may be a large number of habitable planets in the Milky Way. From the estimated data, the number of habitable planets in the Milky Way is at least several billion. This also means that in addition to human civilization, there are also a large number of alien civilizations in the Milky Way, but we have not yet discovered them.

Are there alien civilizations in the galaxy?

Last year, researchers from the University of Nottingham in the United Kingdom published a very interesting research article in the American "Science Daily", saying that through research, they found that there may be at least 36 alien civilizations in the Milky Way.

Moreover, the development level of these alien civilizations is similar to that of human civilization at the lowest level. In short, they can communicate with the outside world and find their companions by sending out signals.

In addition to the Milky Way, the number of alien civilizations may be even more astonishing. Here, we might as well take a look at the "Green Bank formula" proposed in the last century - Drake's formula, which is used to speculate that "maybe The formula for the number of intelligent civilizations in our galaxy and beyond."

According to calculations, the researchers believe that in the vast universe, there are at least billions of large galaxies with a size similar to the Milky Way, and in each large galaxy, there are hundreds of billions of stars. Naturally, even if there were only 36 alien civilizations in each large galaxy, this would be quite astonishing.

After all, counting the number of alien civilizations that may exist in the universe, there are at least tens of billions, or even hundreds of billions. As for why alien civilizations have not come to Earth to find us, or we cannot contact alien civilizations, Some people think that this may be because the distance between civilization and civilization is too far.

For example, the distance between each large galaxy is 2 million light-years away from each other. Even if an alien civilization can fly at the speed of light, it will take 2 million to travel from its own galaxy to another galaxy. For more than a year, of course, even if you are traveling in and out of the big galaxy where you are, it is difficult to visit the entire galaxy. The reason is very simple, because it is so big.

Take human beings as an example, until today, human beings have never left the solar system, and have not even landed on any other planet in the solar system except the moon. Even the United States, which has always been in the leading position in the space field, according to their The plan is to return to the moon around 2024, and around 2030, a manned landing on Mars will be carried out.

And this is only the achievement of the United States itself. Compared with all human beings, it may still take hundreds of years or even longer to achieve complete travel in the solar system and space travel in the solar system.

It takes 4.2 years to fly away from the solar system to the nearest star system, even at the speed of light. However, Einstein once mentioned in his theory of relativity that humans can never fly at the speed of light. It also means that humans may never be able to leave the solar system.

Already for the vast universe, the lifespan of human beings is too short, which also prevents human beings from going further, unless the wormhole predicted by Einstein can be found one day, so that the wormhole in the universe can be realized. "Teleport", you don't need to fly at the speed of light, you can go to farther places.

What are the criteria for a habitable planet?

Now that we have talked about habitable planets outside the solar system, as well as extraterrestrial life and extraterrestrial civilization, in the eyes of scientists, what are the standards for habitable planets?

In addition to the Gliese 581d and Gliese 581g mentioned above, which researchers believe are 100% life-bearing, there are many planets that are all life planets in the eyes of scientists.

For example, Kepler-22b, which is about 600 light-years away from the earth, has an average surface temperature of about 22 degrees Celsius. At the same time, 35 light-years away, there is another planet with an average surface temperature of about 25 degrees Celsius. HD85512b, these planets are among the most special existences in the eyes of scientists.

At present, the criterion for scientists to judge whether a planet is habitable is whether it is in the habitable zone? What is the approximate surface temperature? Is it a rocky planet? Does the surface support the existence of liquid water? Is there a thick atmosphere that protects life on the surface?

In addition, the so-called life planet does not mean that the life on this planet must be a relatively complex life form, or there is intelligent life. Generally speaking, if there are microorganisms invisible to the naked eye on a planet, this It is also a kind of life, and this planet can also be one of the life planets in the universe.

From the above criteria, we can also see that scientists’ assessment of habitable planets outside the solar system actually takes the earth and the solar system as the reference standard. The search for extraterrestrial life, because the environment that may be habitable on earth, is not habitable for extraterrestrial life.

For example, there is a view that the life forms in the universe are not only carbon-based life, but are divided into various life forms, such as silicon-based life, sulfur-based life, etc. Humans have not found it, and cannot. means it doesn't exist.

At the same time, the researchers also found that oxygen is not ubiquitous on extra-system planets, and it can even be said to be very special, which may also mean that alien life does not need oxygen to breathe, just like "Avatar" "The creatures on the planet Pandora do not need to breathe oxygen. In short, it still takes a long time for humans to find extraterrestrial life, let's wait and see!