What is the Milky Way?
The Milky Way galaxy is a huge collection of dust, gas, and stars, including our Sun. The Earth is located inside this galaxy, so it is often called “our home galaxy” or simply “our galaxy.”
It might be hard to believe, but that starry band across the night sky that we can see from the Earth is actually a huge galaxy that extends billions of kilometers around our planet. How big is it? Let’s find out.
The Size of the Milky Way
The Milky Way is the second-largest galaxy in the Local Group of galaxies; the first place goes to Andromeda. The Milky Way is 105,700 light-years wide while the Andromeda Galaxy is 220,000 light-years in width. By the way, the Local Group — a group of multiple galaxies including the Milky Way — extends for roughly 10 million light-years around us in space.
Why is it called the Milky Way?
The name of our home galaxy, like the names of many other astronomy objects, came from the ancient Greek and Roman cultures. Both the Greeks and Romans saw the starry band as the river of milk. The Greeks believed that it was milk from the goddess Hera who spilled it across the sky, and the Romans myth said that the Milky Way was milk from their goddess Ops.
Other cultures had their own myths and beliefs regarding the starry band of light in the night sky:
People in eastern Asia called it the Silvery River of Heaven;
The Finns and Estonians believed it was the Pathway of the Birds;
In Southern Africa, it’s called the Backbone of Night.