Scientiststhink that there has been life on earth for millions of years. However, wehaven't found life on other planets yet. The earth is a planet and it goesaround the sun. And there are seven other planets that also go around the sun.The sun and its planets are called the solar system. The solar system is asmall part of the universe.

    Scientistshas launched many spaceships to explore other planets in the solar system. Somespaceships have gone beyond the solar system. However, no one has discoveredany life in space yet.

    Why has noone from other planets sent us a message? Have they tried to send informationto us? With so many stars in space, are we alone, or is there life on otherplanets in space?