Nowadays many earth-like planets (Kepler 62e; Kepler 62f) are being discovered in the other solar systems by Kepler Space Telescope. These planets are located in "habitable zone" and can consist liquid water at their surfaces with sufficient atmospheric pressure. According to the scientists billions of these planets exist. Habitable zone terms is used to describe "not too hot and not too cold to support life".
It is actually very obvious that there are many other planets which are able to host life and probably the intelligent life. Only in our galaxy there are millions of solar systems which have their habitable zones and planets which may consist an alien civilization.
The nearest of this alien life can even be close to us like 12 light years. In the following years more these earth like planets will be discovered and one day finally we will come across with an alien civilization on a different planet.
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