Science fiction has long been obsessed with the idea of alien life forms and how they may appear. Over the years we have seen little green men, bug-eyed monsters and predatory killers take to the silver and smaller screens to represent our idea of life from outer space. But scientific fact may hold the key to a more realistic depiction of creatures and plants which have adapted to meet the harsh challenges of alien worlds. In the hunt for extra-terrestrial life, astronomers often try to find Earth-sized planets in what is called the'habitable zone' of their host star. This means they are orbiting at the correct distance for liquid water to exist on the planet.

Two astronomy students from the Netherlands have mapped the entire Milky Way Galaxy in dwarf stars for the first time. Their map suggests that there are a total of 58 billion dwarf stars, of which seven per cent have been found in the outer regions of our galaxy. This is the most comprehensive model ever for the distribution of these stars, which are relatively small and shine less brightly. Two astronomy students from the Netherlands have mapped the entire Milky Way Galaxy in dwarf stars for the first time. Their map suggests that there are a total of 58 billion dwarf stars, of which seven per cent have been found in the outer regions of our galaxy.