CBSE Class 9 Answered

The atmosphere and surface conditions of Venus and Mars are not very suitable for life to exist like Earth. For eg - Mars has no global magnetic field that would protect the planet from potentially life-threatening cosmic radiation and solar radiation. Oxidizing soil conditions also do not permit life to occur.

There is no distinct proof to suggest that life does not exist at all on other planets. There is the possibility that life may have once existed on such planets. Also there is the possibility of life existing now, perhaps in a deep underground aquifer on Mars. Some studies show that microbial life is present in other planets like Venus and Mars. Studies are constantly on to determine this.