Scientists said that traces of the existence of hypothetical extraterrestrial civilizations in the solar system should be sought only on Mars or the Moon, because on other planets they had to be destroyed by geological or cosmic processes. The findings of the researchers were published on the website arXiv. Org.

Approximately 3.5 billion years ago, just three planets of the solar system could support life - Venus, Mars and Earth. Even today they are in different parts of the so-called "zone of life", where water can exist in liquid form. After a billion years, Venus turned into a red-hot and "acidic" hell, and Mars into a waterless and frozen desert.

Life and civilizations, if they existed on Mars, Venus or other planets of the solar system, could disappear long before people and multicellular life appeared on Earth. In addition, aliens could simply "migrate" to Earth and die in the course of a cataclysm.

In the course of the new study, scientists decided to calculate whether traces of the existence of such civilizations on other planets of the Solar System. The remains of animals, plants and traces of civilizations on Earth disappear quickly enough due to the action of the forces of nature, the roots of plants and the vital activity of microbes. Due to this, the remains of such "ancient aliens", if they existed on the Earth or other planets, will have a very limited time of existence.

In addition, the Earth's rocks are constantly submerged in the bowels of the planet and are melted down, destroying all possible traces of life and civilizations in them. Such a process usually takes about 300-500 million years, which, according to scientists, is the extreme bar for the existence of traces of "ancient aliens" on Earth.

Mars and the Moon in this respect are more suitable for searching for such remnants of civilizations - their bowels have frozen for a long time, and on the surface of the Moon or in the bowels of the red planet could last much longer than 500 million years. On the other hand, and here the terms of their lives will not be infinite - on Mars artifacts of "ancient aliens" can destroy the wind and other sources of erosion, and on the Moon - micrometeorites and cosmic rays.

Venus is least suitable for such searches, because it turned into a giant greenhouse a billion years ago, and massive volcanic eruptions and renewal of the planet's surface had to destroy the traces of ancient civilizations if they existed on Werner. The same applies to Europe, Enceladus and other satellites of giant planets, whose surface is not stable.

Earlier, Edward Snowden stated that the earthlings can not decipher the code of the messages of aliens. On the air of an American television channel, he said that the universe is so interested in protecting communications that the alien signal can be simply too well encrypted. Therefore, earthlings can not distinguish it from ambient noise.