The Milky Way galaxy contains about 100 billion stars. If you multiply that by the estimated number of galaxies in the observable universe (10 trillion is a modest guess) you get a number that is 1 with 24 zeroes after it: 1 septillion.

David Kornreich, an assistant professor at Ithaca College, said that number is probably much too low because more galaxies will likely be discovered as technology improves.