The theory began when an ancient battle was going on a warrior saw a strange flying object in the sky and thus he was killed. Similarly when a modern war was going on in 1987 a fighter pilot saw unidentified crafts zooming through the air. UFOs are actually unidentified flying objects which have no obvious explanation. People have reported missiles, birds, and swarms of insects, hot air balloons, satellites and weather balloons as UFOs. When the Montgolfier brothers first launched their hot air balloon the people of the village actually thought that they were being invaded by aliens! Similarly when a run out satellite or a space probe crash, the public think they are alien space ships. Well aliens do exist because when the space probes were sent to other planets they were shortly destroyed. There is a probe which called pioneer x which has passed Pluto’s orbit and is now deeply exploring space maybe just maybe the Americans have picked up some unusual data and they are not sharing it with us?!Well there are rumours that the American military has underground storage facilities in which they store alien technology. There is another rumour that on Europa (a moon of Jupiter) that is made entirely of ice and has a sea of alien fish beneath it maybe in the future a space probe might explore it. In the past many electronic telescopes were used to find anything unusual but they could not except new galaxies. Well there is something just wanting to be discovered because there is definitely something beyond Pluto’s orbit. In 1996 astronomers proved that on the surface of Venus and mars there are micro organic life forms that do not come from earth aliens do exist.