How many planets have been proved to have life?

As of July 24th, 20 19, the only known living planet is the earth. Since the middle of the 20th century, human beings have been using the methods of detecting the radio waves outside the earth and observing the potentially livable planets with astronomical telescopes to detect the signs of extraterrestrial life, but there is no definite evidence to show the existence of extraterrestrial life. Some people think that the chances of finding aliens are very small, and many people think that alien life must exist. A large number of reports about aliens, science fiction and movies have enriched the rumors of alien life. The eight planets in the extended data solar system all run in nearly circular orbits on almost the same plane and revolve around the sun in the same direction. Except Venus, the rotation direction and revolution direction of other planets are the same. Comets revolve around the sun in the same direction, mostly in elliptical orbits, and generally have a long period of revolution. The celestial bodies orbiting the sun are divided into three categories: planets, dwarf planets and small celestial bodies in the solar system. Planets are celestial bodies with sufficient mass around the sun. This celestial body: 1. Enough mass to make it a sphere; 2. Small celestial bodies that can empty adjacent orbits. There are eight celestial bodies that are not satellites of planets, or stars, and can be called planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. On August 24th, 2006, the 26th International Astronomical Union was held in Prague, Czech Republic, which redefined the word planet, excluded Pluto from the big planet for the first time, and formed a new classification of Pluto, Ceres and Eris: dwarf planet. A dwarf planet does not need to remove small objects near its orbit. Other celestial bodies that may become dwarf planets include Cedena, Ercus and Chuangshen. From the first discovery of 1930 to 2006, Pluto was regarded as the ninth largest planet in the solar system. However, at the end of the 20th century and the beginning of the 20th century, many celestial bodies similar in size to Pluto were discovered in the solar system, especially Mars, which was clearly pointed out to be bigger than Pluto (according to the data sent back by 20 15 travelers, Mars was still bigger than Pluto), which seriously threatened Pluto's status. Other celestial bodies orbiting the sun belong to the solar system. Satellites (the moon and other celestial bodies) are not small celestial bodies in the solar system because they revolve around planets, dwarf planets or small celestial bodies in the solar system instead of the sun. Astronomers use astronomical units (AU) to measure distances in the solar system. 1AU is the average distance from the earth to the sun, which is about1.500 million kilometers (93 million miles). The distance between Pluto and the sun is about 39AU, and Jupiter is about 5.2AU. The most commonly used length unit for measuring the distance between stars is light years, and 1 light year is equivalent to about 63,240 astronomical units. The distance between the planet and the sun changes periodically with period of revolution. The closest position to the sun is called perihelion, and the farthest position is called apohelion. Sometimes the solar system is informally divided into several different regions: "inner solar system", including four terrestrial planets and the main asteroid belt; The rest is the "outer solar system", including all celestial bodies outside the asteroid belt. Other definitions include areas outside Neptune, and the four big planets are called "intermediate zones". References:

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