- A galaxy is a system of millions, billions or even trillions of stars, gases, dust and dark matter held together by a gravitational attraction.
- There are billions of galaxies in the universe.
- Our solar system is located in the Milky Way.
- The word galaxy comes from the Greek word galaxias meaning “milky.” This is where we get the name the Milky Way from.
- There are different types of galaxies. The main three are Spiral, Elliptical and Irregular.
- Spiral galaxies look like flat disks with spiraling arms. Spiral disks have a lot of gas and dust. Many new stars are created in Spiral galaxies.
- Elliptical galaxies are usually older. They have less dust and gas. New start are not often created in Elliptical galaxies.
- Stars in an Elliptical galaxy are usually close together and look like one big star.
- Irregular galaxies are galaxies that don’t fit into the Elliptical or Spiral group.
- Galaxies are separated large amount of empty space.
- A local group of galaxies is made of about 30 galaxies.
- The three largest galaxies in our local group is the Andromeda Galaxy, the Milky Way and the Triangulum Galaxy.
- It is believed that large black holes are in the center of each galaxy.
- It takes the sun over 20o years to orbit the center of the galaxy. When the sun completes the orbit, it is called a galactic year.
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