This photo shows the Milky Way (from the Latin via lactea), part of our galaxy as seen from Earth. It’s a barred spiral galaxy, essentially a flat disk of at least 100 billion stars. Our galaxy is just one of about 400 billion in the universe, only three of which can be seen by the naked eye. Which means almost everything we see unaided is part of our own Milky Way.

That ribbon of “milk” that forms the Milky Way is composed of stars that can’t be distinguished from each other by looking with the naked eye. It was only resolved into individual stars by Galileo in 1610 with his new telescope. The reason it looks like a ribbon is because we are inside the disk, looking out. Think of yourself inside a faintly colored white glass plate, inside a black room. As you look out through the plane of the plate, you see a white ribbon on a black background.

The Milky Way: Inside, looking out

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