billions!) of stars. As big as galaxies are, they are generally separated by large areas of empty space. There are even clusters of galaxies that are separated by even larger areas of space. Scientists think there are over 100 billion galaxies. Wow, the universe is huge!Milky WayWe live in the galaxy called the Milky Way. The Milky Way is part of the cluster of around 3,000 galaxies called the Local Group. The Milky Way is a spiral-shaped galaxy and is estimated to be made up of around 300 billion stars.Must Read: The Planet Earth and the Universe
Types of Galaxies
There are four main types of galaxies depending on their shape:
- Spiral – The spiral galaxies has a number of long arms that are spiraling around the center. In the center of the spiral galaxy is older stars while the arms are generally made of new stars.
- Barred spiral – This type of galaxies is similar to the spiral but has a long bar in the middle with spirals coming off the ends.
- Elliptical – A mass of stars clumped together in the shape of an elliptical disc.
- Irregular – Any other shaped galaxies is generally lumped into the category of irregular. It is thought that most irregular galaxies are formed by two of the other three types of galaxies crashing into each other.
Also Read: Milestones in Space Exploration
Fun Facts about Galaxy
- The word galaxy comes from the Greek word for “milky”.
- Some scientists think that most of the mass of a galaxy is made up of a mysterious substance called dark matter.
- It is thought that there is a massive black hole in the center of galaxies.
- The closest galaxy to the Milky Way is Andromeda, which is around 2.6 million light years away from us.
- Many galaxies are more than 100,000 light years across in distance.
- It takes over two hundred million years for the sun to orbit the center of the galaxy. This is called a galactic year. A galaxy is a massive group of stars, star clusters, interstellar gas and dust, and dark matter which is all gravitationally bound together.
- There are four galaxies that can be seen from Earth with the naked eye: the Milky Way, the Andromeda Galaxy, and the Small and Large Magellanic Clouds.
- The idea of a galaxy was first realized by Thomas Wright in 1917.
- The most common type of galaxies that we have found to date are dwarf elliptical galaxies.
- The Hubble Space Telescope has been instrumental in us being able to study distant galaxies and understand about the different types of galaxies.