Is there a second solar system in the universe?

Why is the Kepler-90 star system called the second solar system? First of all, the only star in the Kepler-90 system is similar to the sun, and like the sun, there are eight planets around this star, which means that this system is as prosperous as the solar system.

This is the first system discovered by humans outside the solar system that is similar to the solar system family. It is also the extrasolar star system with the most planets discovered by humans so far (in this article, "extrasolar" refers specifically to outside the solar system, not outside the Milky Way).

What Kepler 90 looks like: The so-called Kepler 90 is the 90th star with a planet discovered by the Kepler Space Telescope. This star is located in the direction of Draco. Its mass is about 1.13 times that of the Sun. Like the Sun, it is a yellow dwarf star. Its surface temperature is slightly higher than that of the Sun, about 5930K, so its brightness is slightly higher. Its absolute magnitude is about 4.54, a little brighter than the Sun's 4.83. However, because it is 2545 light-years away from us, its apparent magnitude is only 14, and it is invisible to the naked eye.

I have said many times before that the brightness of celestial bodies is measured by magnitude. The smaller the magnitude, the brighter it is. There are also negative numbers. The more negative the magnitude, the brighter it is. The brightness difference between each magnitude is 2.512 times. I will not go into details today.

Now you know why Kepler-90 is the Sun's brother, right? It is about the same size and brightness as the Sun. But it is obviously the Sun's younger brother, because it was born 2.6 billion years later than the Sun, only 2 billion years old, while the older brother, the Sun, is 4.6 billion years old.

What is even more strange is that the families of these two brothers have 8 great disciples, or children. The sun has 8 planets, and Kepler 90 also has eight planets. These planets are counted from the closest, in order of b, c, i, d, e, f, g, h. The closest planet is called Kepler 90b, and the farthest is called Kepler 90h.

According to the naming principle of the eight planets, the original order is b, c, d, e, f, g, h, i. The i should be at the end, that is, the farthest. However, since the i planet was discovered last, and the first seven planets had been discovered and named long ago, if we have to rearrange the order, it will be a mess. Because people have been familiar with and used those planet numbers in many materials for many years.

Therefore, star i became the third party, intervening between c and d.

The Kepler Space Telescope was launched by NASA in 2009 with the main mission of searching for exoplanets. The method of discovering planets is the transit method, which is to "guess" based on the changes in the brightness of stars when the planets move between humans and the stars. Therefore, this method can only discover planets and roughly know the size of these planets. It is difficult to determine the mass of the planets, let alone see the appearance of the planets.

The data obtained by the transit method shows that the eight planets of Kepler 90 are all larger than the Earth. The largest one is Kepler 90h, with a radius 11.32 times that of the Earth, which is similar to Jupiter, but a little bit larger; the smallest one is Kepler 90c, with a radius about 1.2 times that of the Earth.

There are other methods for observing exoplanets, such as the gravitational perturbation method, which estimates the mass of a planet by observing the influence of the gravitational force of the planet's motion on the star. Using this method, scientists have preliminarily learned that the masses of the three planets in the Kepler-90 system, I, G, and H, are about 2.5 times that of the Earth, 0.8 times that of Jupiter, and 1.2 times that of Jupiter, respectively.

From the mass status of these planets, it can be seen that the masses of these planets are similar to those of the solar system. The masses of planets close to the stars are relatively small, and they are terrestrial planets such as the Earth, Venus, Mars, and Mercury; while the masses of planets far away from the stars are relatively large, and they are gas planets such as Jupiter, Saturn, Uranus, and Neptune.

The high similarity between the Kepler 90 planetary system and the solar system planetary system is determined by the universality of the star and planetary system formation process. This has been mentioned many times in the past, so I won’t talk about it today.

What does Kepler 90i, the planet most like the Earth, look like? In fact, NASA has been paying attention to the Kepler 90 star since 2009. The Kepler telescope uses a photometer to observe whether there are transit events with a decrease in brightness of this star. Since the discovery of the first planet in 2013, seven planets have been discovered orbiting Kepler 90. It was not until 2017 that Kepler 90i was finally discovered.

This discovery was made by "picking up leaks", that is, combing through the past observation data of the Kepler telescope. According to NASA, this discovery also benefited from the application of new computer calculation tools, that is, the use of IA (artificial intelligence). It was found by Google engineer Christopher Shalu and Austin University astronomer Andrew Vanderburg through IA, following the weak signals that were previously ignored.

The study found that this planet is ranked third from the Kepler 90 star, exactly the same as our Earth in the solar system, and is a rocky planet like Earth, with a radius 1.32 times that of Earth and a mass about 2.5 times that of Earth. So, is there life or civilization on it?

Research shows that this possibility is very small because the planet is too close to the host star, only about 0.1234AU (astronomical unit, 1AU is about 150 million km), and its orbital period is only 14.45 Earth days, which means it takes about 14 days to orbit the star, while the Earth orbits the sun once a year.

In the solar system, Mercury is the closest to the Sun, at about 0.38AU. Kepler 90i is much closer than Mercury is to the Sun, so it is baked by the high temperature of the star and its surface temperature is very high, at least reaching the surface temperature of Mercury or Venus, which is about 500°C.

Being so close to the star, even if there is an atmosphere, it will be evaporated and blown away by the stellar wind, so it is unlikely that Kepler-90i has an atmosphere. The planet's rotation may have been tidally locked by the star's gravity, that is, only one side is always facing the star, and the other side is always facing away from the star. In this way, the side facing the star is always scorched by the star's heat waves, while the side facing away from the star is as cold as an ice cave, with a temperature below -100℃.

Under such conditions, it is difficult for liquid water to exist, so it is unlikely that Earth-like life could be born and survive there. However, some people believe that on such planets, there is a suitable temperature near the terminator (that is, the boundary between the sun and the sun), and there may be liquid water and conditions suitable for the existence of life.

However, with no atmosphere and such a fast orbital period, the probability of life and civilization existing on this planet is too small. Could a miracle happen on this planet? Star H is exactly 1AU away from the star and is a giant planet like Jupiter. The probability of life existing on this gaseous planet is even smaller.

Kepler-90 is just a mini solar system. Kepler-90 is a mini solar system not because of its main star, which is bigger than the sun. But all the planets are too close to the star. The farthest star, h, is only about 1AU away from the main star, which is the same distance as the earth is from the sun. Between h and the main star, there are 7 planets orbiting closely.

In the solar system, the closest planet to the sun is Mercury, about 0.38AU; the farthest is Neptune, about 30AU. Therefore, the solar system planetary system is 30 times larger than the Kepler 90 planetary system. In addition to Neptune, there is the Kuiper Belt, which contains many icy dwarf planets, Pluto being one of them, with an average distance of 40AU from the sun.

In the 10 years since the Kepler Space Telescope was put into service, it has found 2,662 exoplanets, accounting for more than 60% of the exoplanets discovered by humans so far. It has also found a variety of planets similar to the Earth, dozens of which are in the habitable zone, with the hope of life. However, due to the overall weakness of human observation methods, no evidence of the existence of extraterrestrial life or civilization has been found.

Now that the Kepler Space Telescope has been retired, many space telescopes have inherited its unfinished work. Recently, NASA has launched the most expensive and advanced Webb Space Telescope in history. This telescope, which has cost $10 billion to develop and launch, has comprehensive functions that are many times more powerful than the previous Hubble Space Telescope. In theory, it can see the earliest galaxies formed after the Big Bang, that is, the infant universe.

As scientific observation capabilities improve, will we discover more secrets of the Kepler 90 galaxy? Or perhaps extrasolar life and civilization will be discovered soon? Of course, the premise is that extrasolar life and civilization really exist, and the density is not too sparse. What do you think? Welcome to discuss, thank you for reading.

The copyright of Space-Time Communication is original. Infringement and plagiarism are unethical behavior. Please understand and cooperate.