A group of scientists from NASA Jet Propulsion Laboratory has put forward the hypothesis, that the Universe is full of the terrestrial planets, on which surface located oceans and seas of plain water, so they can be generated life, like Earth's. This hypothesis was proposed based on analysis of images of space observatory "Herschel" - was established stars, around which there are clouds of rarefied water vapor, for example, around the star TW Hydrae, located in the constellation Hydra at a distance of 175 light years from Earth, located a clouds of rarefied water vapor. Scientists believe, that comets may carry the water on the planets, collecting it for a long period of time from the clouds of rarefied water vapor. More recently, it was found, that the isotopic composition of water in comets in the solar system is similar to the isotopic composition of water in the oceans on Earth, and therefore very likely, that the comet brought most of the water on Earth.