What is the Milky Way?
The Milky Way is the galaxy that contains our solar system. It is a barred spiral galaxy about 100,000 light-years across, holding hundreds of billions of stars.
From Earth, we see the Milky Way edge-on as a hazy band of light across the night sky, best seen from dark places away from city lights. The name comes from ancient Greek and Roman stories that compared this band to spilled milk.
Our solar system lies in one of the spiral arms, about 26,000 light-years from the center. The Sun takes about 230 million years to complete one orbit around the galactic center. At the center lies a supermassive black hole called Sagittarius A*, with about 4 million times the mass of the Sun.
A galaxy among billions
The Milky Way is one of perhaps hundreds of billions of galaxies in the observable universe. Its nearest large neighbor, the Andromeda Galaxy, is expected to merge with it in billions of years.
Did You Know?
In 2022, the Event Horizon Telescope released the first image of Sagittarius A*, showing a ring of glowing gas around the black hole's shadow.