Kepler discovered many livable planets, which have similar seasons and climate with the earth.

The Kepler telescope was built with only one purpose: to observe every region of the Milky Way and look for exoplanets. During his lifetime, Hunter observed hundreds of thousands of stars and discovered thousands of exoplanets. The Delta 2 rocket was launched in 2009 as part of NASA's discovery program.

Kepler's mission is to constantly scan every fixed sky in the Milky Way for planetary systems. When it was launched, the largest primary mirror in its history was sent into space, and it also had a 96-megapixel camera to process light. Astronomers are interested; How many stars have planets orbiting them? How many of these extra planets of the solar system or exoplanets are suitable for the development of life?

During his nine years in space, Kepler observed 530,536 stars and confirmed the existence of 2,662 new exoplanets. These exoplanets are different from any planet we have seen in the solar system before, and most of them are much larger than the earth. Their orbits are so close to the stars that they complete a revolution every few days, and they also discover a very strange planetary world.

Other exoplanets the size of Jupiter are not surrounded by one star, but two stars. If you stand on the surface of one of the planets, you can see a "double star sunset". Kepler's record is; It successfully discovered the planet world the size of the earth and kept a safe distance from their host stars in a place called "livable zone" or "livable zone".

The temperature here is enough for water to condense on their surfaces, but it is not cold enough to completely freeze. Although there is no guarantee of life in this area, the existence of water is important, because as we know, it is the foundation of life. Scientists announced that the exoplanet discovered by Kepler was named K2 18b. They found signs of liquid water in the atmosphere of this planet.

K2 18b is located at 124 light years away from the earth, and its mass is about 8 times that of the earth. In all its main sequences, there is also a "red dwarf" named Kto 18. "Red dwarf" is the smallest and coldest star in the Milky Way, and it is also the most common type of star so far. According to Kepler's data, astronomers estimate that 6% of "red dwarfs" have a planet the size of the earth in the "golden zone". Finding water on the surface of such a planet is a milestone in the search for a potentially livable alien world.

K2 18b is also the first planet with water among all exoplanets discovered by Kepler in the "livable zone" of stars. Kepler first discovered this planet on 20 15. Since then, its composition has been studied by other telescopes, such as Spitzer and Hubble Space Telescope. Kepler mainly uses the so-called transit method to find exoplanets.

It essentially means. If a planet passes by a star, the light emitted by the star will dim slightly, which is how we judge that there is a planet. However, it is very challenging to detect the "transit" of extrasolar planets. For example, the diameter of the earth is much smaller than that of the sun, so for an external observer of the solar system, this process will only darken the output of the sun by 0.008%. Kepler's camera must be sensitive enough to detect this new change in luminosity in the same way.

As early as 20 14, "Kepler" discovered an exoplanet that might be habitable for the first time, which ignited the imagination of space fans all over the world. Now, a new study shows that this exoplanet may also have a season and climate similar to ours. A new study by Georgia Tech University analyzed the rotation and axial tilt of this planet, and found that its tilt is stable, just like the earth, which makes it possible to have regular seasons and a stable climate.

Research universities all over the world are doing similar research on large-scale capital databases. In fact, in recent years, those discoveries that have been preserved before, those that have been rejected as potential "double-sided exoplanets" due to the era of algorithms, are being re-explored. These misleading reports are now being slowly reanalyzed along with data from other telescopes.

One of the planets is Kepler 1649c. In mid-2020, when it passed through the known "Planet 28" and matched the new data of the "Transit" exoplanet survey satellite (or tess), astronomers confirmed the existence of another exoplanet with very favorable conditions. It is located 300 light years away, and its size and estimated temperature are very similar to those of the earth. This newly discovered alien world is only 1.06 times larger than our own planet.

In addition, the amount of starlight it receives from the host star (also a red dwarf star) is 75% of the amount of light that the earth receives from the sun, which means that the temperature of the exoplanet may be similar to that of our earth. "Kepler 1649c" provides another example of an earth-sized planet in the "livable zone": a red dwarf.

But before we migrate, it is very important that of the 10062 exoplanets discovered by Kepler in 20 16, only 16 are located in the "golden zone", and some of them are neatly locked with their parent stars, which means that only one hemisphere of this planet faces this star. This is not ideal for life. Other planets are more like a small version of Neptune than a big version of the earth. Planets like Neptune have a considerable hydrogen coating around any water layer on the core surface of rocky planets. If the hydrogen layer is too thick, the temperature and pressure of the water layer will be too high to support life. Most importantly; Although the "red dwarf" is colder, it is more active than the "sun-like" star.

Therefore, this planet may be exposed to more harmful ultraviolet radiation than we are used to on earth, because the temperature of this surface may be between 100 and16 degrees Celsius, or between 73 and 47 degrees Celsius. This means; On average, the earth's surface may be colder than Antarctica, or hotter than the most expansive desert on earth. Unfortunately, however, we don't have the technical knowledge to study the composition and atmosphere of these alien worlds and answer all these questions comprehensively.

But we are not desperate. According to the statistical analysis of all observation data, astronomers now estimate that; One fifth of the stars like the sun have planets the size of the earth, and the surface temperature is conducive to the existence of life. For example, a "sun-like" star in the Milky Way alone has billions of potential "livable terrestrial planets".

Although Kepler is committed to finding potential livable planets, in fact, most of its discoveries have strange worlds that are not suitable for life, but these discoveries are fascinating. Like the "gas giant planet", it is a planet mainly composed of hydrogen, helium and other gases, with a relatively small rock core, also known as "hot Jupiter". These planets orbit very close to their "home star" and exist in large numbers.

For example, a fascinating example of "gas giant planet" is Coy5A, which was first discovered by astronomers as early as 2009. At that time, this elusive alien world was the second planet discovered by Kepler. It emerged from the cracks in the universe ten years ago, firstly because of a lot of data, and secondly because astronomers noticed that the main Coy5A star had another companion, which made it difficult for them to analyze it.

In fact, the planet Coy5A is more complicated than researchers realized at that time. At that time, scientists had determined that Coy5A actually contained three stars, but it was not clear whether there was the mass of Planet B.. Or whether the signal in 2009 was generated by one of the companion stars, but because of the extra data provided by the test satellite, scientists can now confirm the existence of A B planetary objects with stable orbits in multi-star systems, which is a rather rare discovery.

The discovery of Kuwait 5 is expected to add a lot of knowledge to our understanding of the formation of planets Other types of exoplanets include "super-Earth", which are heavier than the Earth but lighter than ice giants such as Neptune and Uranus. They can be composed of gas, rock or lava planets, and there is a super density and greater heat around their parent stars (some of them are called "titanium planets", which is probably the residual reason for the evaporation of "hot Jupiter").

Troy is a planet of various sizes found in strange places, sometimes even accompanied by larger planets, but it has not been confirmed so far, because Kepler finally retired on 20 181October 30. Due to the exhaustion of fuel, the mission control center issued a termination order the following month, and the telescope was deactivated. Coincidentally, Kepler's retirement happens to be the 338th anniversary of John Kepler's death, but Kepler's name is no longer used.

These incredible discoveries show that in the near future, astronomers will use new advanced telescopes on the ground and in space to gain a deeper understanding of Kepler's countless experiences. One such telescope has been planned to go into space in 20021year. James webb telescope will take a close look at some objects that used to be Kepler, hoping to bring us closer to answering this question: Are we really alone in the universe?