Let’s consider galaxies first. There may be 100,000,000 galaxies, because an estimated 50 billion galaxies are visible with modern telescopes. Every galaxy must have a number of stars in it, as many as hundreds of billions. Now we all know that stars have planetary systems. Then it is also a well known fact that the dimming and brightening of a star is when a planet crosses its disk. Also, it is believed that every star has a planetary formation around it. Now if galaxies are there, and every galaxy has planets in it, then there is possibility for planets to have water or some form of life on them.
In "The Day the Earth Stood Still," a remake of the 1951 science-fiction classic, an alien named Klaatu (played by Keanu Reeves, right) visits Earth to save us humans from ourselves. The story is a work of science fiction, with the emphasis on fiction, says Seth Shostak, a senior astronomer at the SETI Institute and a technical adviser on the film. For example, to be able to detect a dangerous buildup of carbon dioxide in our atmosphere and come save us from global warming, an alien that could travel at light speed would have to reside no more than about 50 light-years away. "I doubt that there are any aliens that close," Shostak says. And even if there are, "they might not care about our problems." 1. Scientific accuracy aside, Shostak says the film could hook a new generation on space science, just as the original film helped direct his career, which is dedicated to the search for E.T. As kids stumble out of the theater, they might ask, do aliens exist?
With so many stars, alien life is probable
Shostak notes that there is no direct proof for any life beyond Earth, but the universe is home to a lot of stars. And as research over the past decade has shown, perhaps at least 50 percent of those stars harbor planets. Shostak estimates