Science
What is A galaxy?
A galaxy is an enormous system of stars, gas, dust, and dark matter held together by gravity. Our Sun is one of hundreds of billions of stars in the Milky Way, and there are estimated to be trillions of galaxies in the universe.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains a galaxy.
Key things to understand
- 1A galaxy holds millions to trillions of stars bound by gravity.
- 2Common shapes: spiral (like the Milky Way), elliptical, and irregular.
- 3Most have a supermassive black hole at their center.
- 4There are an estimated two trillion galaxies in the observable universe.
Frequently asked questions
- What galaxy do we live in?
- The Milky Way, a spiral galaxy containing our Sun and hundreds of billions of other stars.
- How many galaxies are there?
- An estimated two trillion in the observable universe.
- What holds a galaxy together?
- Gravity — including the pull of dark matter, which makes up most of a galaxy's mass.