Do other races of creatures very different or perhaps quite similar to ourselves exist on distant planets? This desire to explore beyond the confines of our world and to imagine what possible life forms could exist on other planets has led science fiction writers to describe all kinds of strange creatures. In his book, The First Men on the Moon, H.G Wells tells of a species living in the crates and caves of the Moon that he called the Selenites. These creatures resemble giant, intelligent ants. OF course, we are aware today that no such creatures exist and there never has been any form of life on the Moon. There have been other creatures from the pages of science fiction such as the Meckons with tiny green bodies and huge heads whom Dan Dare met in his space travels in the Eagle comic.
These are just a few of the imaginary men from outer space, but what are the possibilities of actual life forms? The first point to make is that there is little to be gained from trying to picture weird and wonderful creatures sprouting radio antennae from their heads and breathing liquid ammonia. We should try confine ourselves to examining whether or not there is any chance of living systems much like our own somewhere else in the Universe. It must also be remembered, however, that a living world elsewhere could be more or less developed than our own. In other words it could still be at the stage of primitive life forms or thousands of years more advanced than our own world.
Scientists have attempted to calculate how many galaxies there are in the Universe and how many solar systems are contained within these galaxies in an effort to work out how many planets there might be similar to our own. Even the most cautious would probably agree that the number of planets in the Universe similar to our own probably runs into the thousands. This means that the chances are heavily in favour of there being many other worlds just like our own in which there are plants and animals and humans breathing air made up of oxygen, nitrogen, carbon dioxide, and a few other gases.
Are these intelligent creatures trying to make contact with us using radio waves? Some people think so, but of course, they may be thousands of light years away so that by the time we receive any message, they could be extinct. The possibility exists that we have already been visited by spacemen and that such wonders of the world as the pyramids of Egypt were constructed with their help. Perhaps soon we shall know more of the creatures from outer space.