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Extraterrestrial life is life that is not from the planet Earth. It is not known if there is any extraterrestrial life. There is no proof that it exists, though it is believed that a large percentage of people believe in them.
Most scientists believe that if extraterrestrial life exists, its evolution would have happened in different places in the universe. Others believe that life started on a small number of planets and spread to other planets.
Extraterrestrial life forms are often referred to in popular culture as aliens or ETs, and sometimes also martians.