Scientists believe there are about 100 billion galaxies, or systems in space comprised of stars, dust and gas. There is no way for researchers to view all parts of the universe, so specific areas have been viewed to count the number of galaxies there in order to create an estimate for the entire universe. In 2011, the Hubble telescope was used to view an area of the sky about one-tenth the diameter of the moon as seen from Earth, and about 10,000 galaxies were found in that area of the sky. The number was then multiplied to estimate the number of galaxies in the universe, but the actual number might be even higher. For example, one supercomputer simulation estimated that there could be as many as 500 billion galaxies.
More about galaxies:
- There are thought to be about 50 billion planets in the Milky Way galaxy, 500 million of which could possibly be inhabitable.
- Most galaxies are estimated to be elliptical, but more than 75% of the galaxies that can be seen are spiral in shape. This is because an elliptical galaxy has a black hole in the center, making it difficult to see.
- Ten galaxies can be seen from Earth without the use of a telescope.