Can people really live on other planets? Is there anyone there? Can people live by aliens?

In fact, there is no place suitable for human habitation except the earth. But if we really consider alien living, Mars may be the most ideal in the solar system. There are three reasons: First, the temperature of Mars is the most suitable for human habitation compared with other planets. The average temperature is around MINUS 40 degrees Celsius, but humans can live near the equator of Mars, with the average temperature around freezing point and as high as 20 degrees Celsius in summer. The temperature difference between day and night of the moon is over 200 degrees Celsius, which is not suitable for living. (It has something to do with the lack of atmosphere on the moon) Secondly, Mars has sufficient atmosphere. Although it is all carbon dioxide and a small amount of nitrogen, it can at least block a lot of radiation from the universe and the impact of small meteorites. If you are on the moon, you will be irradiated by any cosmic radiation source, and the smallest sandy space material will hit the surface. And there is wind (storms on Mars are much more severe than those on Earth), which can be used as a source of electric energy. Third, there is a lot of ice at the poles of Mars. In ancient times, the temperature of Mars was warmer than it is now, and water once existed in the form of liquid. (Mars has a large number of ancient dry rivers) Later, Mars gradually became cold, and the rainfall at the poles solidified rather than flowed away. It has stayed there for a long time. Humans can make full use of these water resources. The moon, of course. At present, there are many researches on the moon. Of course, it is not impossible to have the moon, because it is closer. Mars. Only Mars has the possibility of water. Although the moon is close, it is not necessarily suitable for living. Mars, the moon is just a satellite. Human beings need to live. Without the moon and Mars, which one is more suitable for human habitation?