Spiral Galaxy Lesson for Kids: Definition & Facts

Instructor: Suzanne Rose

Suzanne has taught all levels PK-graduate school and has a PhD in Instructional Systems Design. She currently teachers literacy courses to preservice and inservice teachers.

Did you know that there are different types of galaxies? In this lesson, you'll find out some interesting information about spiral galaxies, including how they got their name and what they look like.

The Milky Way Galaxy

Our Earth, the stars, and the other planets in our solar system are all part of the Milky Way galaxy. A galaxy is a group of stars, gases, and space dust that's held together by gravity. But not all galaxies look alike. The Milky Way galaxy is called a spiral galaxy because of its shape. Let's find out more about spiral galaxies.

What Do Spiral Galaxies Look Like?

All spiral galaxies look like balls with arms. They have a center part, or bulge, and then one or more arms that swirl out from the center. The spiraling arms give them their name. About one out of every ten spiral galaxies has only two arms, but six out of every ten spiral galaxies have more than two arms.

A Barred Spiral Galaxy

Depending on which way the galaxy is facing, it can be easy or difficult to see the arms. Some galaxies have arms that are very close to the bulge, and others have arms that are loose. Astronomers, scientists who study the stars and planets, use these features to help identify and name galaxies.

Some spiral galaxies have a bright line that looks like it's going through the middle of the galaxy. These spiral galaxies are called barred spiral galaxies because the line looks like a bar through the middle of the galaxy. About two-thirds of all spiral galaxies are barred, including our Milky Way galaxy.

Spiral Galaxies in the Universe

Lots of dust and gas can be found in the arms of a spiral galaxy; because of this, they're often places where new stars are being formed! The gas and dust are used to create new stars.

The bulge of a spiral galaxy is usually made up of old stars. For this reason, there aren't many new stars formed there. Astronomers believe that the bulges of spiral galaxies contain huge black holes. A black hole is an area in space that has such a strong gravitational pull that nothing can escape from it.

As the gas in the arms of a spiral galaxy burns up, or is used for creating stars, a spiral galaxy will change in shape and become an elliptical galaxy. Elliptical galaxies have roundish-shapes that can be like circles, or might be long and flatter, almost like a cigar.

Some Well-Known Spiral Galaxies

We know the most about the Milky Way galaxy, since it's our own galaxy, but there are some other well-known spiral galaxies that astronomers have investigated.

Sombrero Galaxy

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