In recent years, astronomers have discovered thousands of planets and planetary systems orbiting around nearby stars. Some are small and rocky like the Earth, whilst others are gas giants like Jupiter. It is now believed that most stars in the Universe could have planets orbiting them and that some of them may have physical characteristics that resemble those of the Earth. The sheer number of stars in the Universe, each potentially with orbiting planets, along with the ubiquity of pre-biotic compounds, suggests that extraterrestrial life may be likely.
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