Interactive · 2 questions
Introducing Galaxies
The dictionary definition:
Galaxy: a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
My definition:
Galaxy: a body that contains millions of stars
What are three types of galaxies? (Check all that apply)
Yes! Elliptical, irregular, and spiral galaxies.
What is a spiral galaxy?
The name alone says it all. A spiral galaxy is a galaxy constructed mainly with one or more spiral arms.
Got it?
What is a elliptical galaxy?
An elliptical galaxy has a ellipsoidal shape and a smooth, rounded profile. Unlike the spiral galaxies with organization and structure, elliptical galaxies are more 3-D, without much structure, and their stars are in almost random orbits around the center.
Now you know what spiral and elliptical galaxies are, what do you think irregular galaxies are? (Check all correct definitions)
Correct!
In addition, galaxies contain ten times as much dark matter as there are stars. It's all held together by...
What do you think?
Gravity!