The usage of ‘alien’ is seen in different places: biology, astrobiology, fiction, films, stories, computers and many more. Though the meaning remains the same, each of these is different situations. While biology refers to an animal or plant coming from outside as ‘aliens’, astrobiology deals with extra terrestrial life from outside earth as ‘aliens’. These later concept has been a subject of writing for many authors and a theme fro different world class movies.

There are no proven and accepted evidence to proof the existence of ‘aliens’. It has been a hot topic of discussion among scientists and researchers. They come up with contradictory opinions. The existence of life in moon and planets like mars and Venus has been the interesting area of studies for them. But no direct proof for life has been observed or there is none said to have seen an alien. Thus it continues a mystery.

Though none can prove how an alien looks, it is funny or more interesting that different physical appearance are given to them by different people according to their imagination. This is seen in different movies and fiction stories. Their looks are completely featured according to the imaginative power of its creators and there is no controversies prevailing in this area. Each one can come up with his own ideas.

The separate wing of science under the name ‘astrobiology’ is conducting detailed analysis on various aspects of life to prove or disprove the various ideas coming up in the area of ‘aliens’.  According to the supporters of the concept of ‘aliens’, life can exist outside the earth in moon or other planets of solar system. They are pointing out the existence of conditions similar to earth in these places and argue that they can balance life.

Beliefs in regard to the aliens existed from time earth was born. Different civilizations and different nations have faiths and beliefs according to their cultures and traditions. Religious narrations are seen in Islam, Jewish and Christianity that argue on different ideas relating to the subject. As science evolved, man discovered instruments to look into the world outside. The earlier thoughts were replaced or modified. Anyway it continued through 20th century to the 21st century. The research always oriented at testing the essential conditions of life and whether this existed outside the globe.

It is never expected that this controversies will come to an end in the near future. The concept of aliens gets different forms and there are as many ideas relating to it as there are individuals. They get ideas from beliefs and myths and introduce supporting factors to win in the concerned debates.

Man’s curiosity is always the driving factor behind all these research and studies. ‘Aliens’ have been an interesting subject for man in his debates. It is this curiosity that is being exploited in films by efficient moviemakers and has proved successful. Still then man shows an reluctance at times when a real life situation comes to accept aliens as part of their environment. This is considered as a human habit of a hesitation to go with strangers.