2023-07-28 20:50:06
Park Jong-jin The universe is made up of stars. A star is called a star in Chinese characters, and a group of hundreds of billions of such stars is called a galaxy. In particular, the galaxy to which our star, the sun, belongs is called the Milky Way. A star is a celestial body that produces light and heat by nuclear fusion. The most familiar of the stars we know is the sun, but if you see the sun near the North Star, it will be nothing more than a twinkling little star like any other star in the night sky. A celestial body that revolves around such a star is called a planet. In the case of the sun, a total of eight planets orbit: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto, which orbited the outermost was excluded from being classified as a dwarf planet in 2006. A satellite (衛星, satelite) is a celestial body that orbits around a planet. Therefore, a satellite orbits around a planet, and a planet orbits a star. , The moon revolves around the earth, and the earth revolves around the sun. Hundreds of billions of stars like the sun gather to form galaxies, and about 2 trillion of such galaxies gather to form the universe. Mercury and Venus, which orbit the sun closest, have satellites. Then there is only one satellite named Moon in the orbiting Earth. The Moon is too big to be a satellite, so it can be seen as a pair of planets, but the Moon is a satellite of the Earth. Outside the Earth Jupiter, the largest in the solar system, has a total of 95 satellites, and the first satellites found on another planet other than the Earth’s moon are four satellites orbiting Jupiter. It is called the Galilean satellite because it was discovered by Galileo, who improved the performance of the telescope. Then, there are as many as 145 satellites revolving around Saturn in orbit. At this point, it is difficult to name them individually. In 2019, 20 satellites of Saturn It was discovered at once, then 12 satellites of Jupiter were newly added in February 2023, and 62 moons of Saturn were discovered again in May 2023. Uranus orbiting the outer part of the solar system has 27 satellites, and the last The planet Neptune has 14 satellites orbiting it. In addition, satellites orbiting dwarf planets and asteroids have also been confirmed, with the smallest being only 45 m in diameter. Then there were protoplanets orbiting the sun, and satellites were created when the remaining material was pushed away by the solar wind and captured by the gravity of a nearby planet. Therefore, in the case of a planet close to the sun, it misses a lot of dust passing by at high speed, so naturally the number of satellites is small, and the farther away the planet is from the sun, the faster the dust passing by it decreases, so it is easy to be captured by the planet’s gravity, so the number of satellites decreases. many. For this reason, Mercury and Venus, which are closest to the sun, have no moons at all, while Jupiter and Saturn, which are farther from the sun, have many moons. Of course, Jupiter and Saturn’s strong gravitational pull from their large bodies was able to trap much of the material passing by them. (Writer) Park Jong-jin
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