Recently, two scientists discovered that two planets outside the solar system may have the conditions for life, which even aroused a fever of "extraterrestrial civilization". Some scientists think that aliens certainly exist, but it is not easy to find a planet with life like Earth. If there are planets, there is not necessarily life; Life does not necessarily mean more advanced life, it requires that the position of the planet to the parent star must be just right. According to such conditions, there are only about 6.5438+0 million planets in the Milky Way. In this 654.38+million, there must be a series of conditions for the formation of life, including water, oxygen and various chemical elements. And if the aliens on those planets have a highly developed civilization, and their history of sending radio signals to the sky is much earlier than that of the earth, which has been 1 10,000 years (our earth is only 100 years old), then it is possible to count down only 250 planets. If they are evenly distributed in the Milky Way, the latest one is 4,600 light years. In the universe, there are 654.38 billion extragalactic galaxies like the Silver System.