What is a satelite galaxy?

Our sun is part of a massive collection of stars in the Milky Way galaxy. These hundreds of billions of stars orbit the galaxy’s center. But did you know that there are things that are even bigger orbiting the Milky Way’s center? Other galaxies orbit it too!

These less massive galaxies have their own impressive collection of stars, which all orbit their own center; but the galaxies and everything in them orbit our galaxy too. 

It’s as if our galaxy is the sun and those other galaxies are planets. Astronomers call them “satellite galaxies.”



What Is a Satellite Galaxy?


Where are they and what are they like?

Unlike our spiral galaxy, this one lacks a clean spiral shape. Some scientists think that is because the Milky Way and other galaxies are pulling and warping it.

In terms of distance, there are two contenders for closest satellite galaxy. One group of stars is small enough that astronomers consider it a “dwarf galaxy.” The other group is so close that they still debate whether or not it is part of our galaxy or its own dwarf galaxy.


Where does one galaxy start and the other end?

Some scientists don't thinkthe Canis Major cluster of stars is actually its own galaxy or dwarf galaxy. Instead they think it is just a dense area of faraway stars that are still part of the Milky Way. 

Either way, it is clear that this bunch of stars has been pulled very close to our Milky Way by our galaxy’s massive gravity. 

Over time, this could be the fate of other satellite galaxies in the area. They could all one day merge into an even larger Milky Way galaxy!


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