What Is the Milky Way? Our Galaxy, Explained

The Milky Way is the galaxy we live in — a vast, spinning collection of stars, gas, dust and dark matter that includes our Sun and everything we can see in the night sky without a telescope. It holds somewhere around 100 to 400 billion stars, and our Sun is just one ordinary star among them, sitting partway out from the center. The hazy band of light you can see arching across a truly dark sky? That’s the Milky Way seen edge-on, from the inside. Here’s how our galaxy works, in plain English.

What the Milky Way is

A galaxy is a huge, gravitationally bound system of stars and their planets, plus the gas and dust between them. The Milky Way is our home galaxy. Because we live inside it, we can’t take a photo of the whole thing from the outside the way we can other galaxies — every picture of “the Milky Way” from outside is an artist’s impression based on careful measurements.

It earned its milky name from that faint, glowing band of light across the sky, which ancient observers thought looked like spilled milk. We now know that band is the combined glow of countless distant stars in the galaxy’s crowded disk.

How big the Milky Way is

The numbers are hard to picture, so it helps to use light-years — the distance light travels in a year.

The galaxy’s main disk is roughly 100,000 light-years across.
Our Sun sits about 26,000 light-years from the center — out in the suburbs, not downtown.
The whole disk slowly rotates, and the Sun takes something like 225 million years to complete one lap around the galaxy.

Put another way: light, the fastest thing there is, would need 100,000 years just to cross from one edge of the visible disk to the other.

The shape of our galaxy

The Milky Way is a barred spiral galaxy. That means it has:

A flat disk with sweeping spiral arms, where most of the bright young stars, gas and dust live. Our Sun sits in one of these arms.
A central bulge crossed by a bar-shaped concentration of stars.
A halo — a fainter, roughly spherical cloud of older stars, ancient star clusters and a great deal of unseen dark matter surrounding everything.

At the very center lurks a supermassive black hole called Sagittarius A*, with the mass of about four million Suns. It doesn’t “suck in” the galaxy — most stars, including ours, simply orbit at a safe distance. For more on how these objects work, see our explainer on what a black hole is.

What’s inside the Milky Way

Beyond its hundreds of billions of stars, the galaxy is filled with the raw material for making more. Giant clouds of gas and dust drift between the stars, and in some of them new stars are actively forming. These clouds are nebulae — see what a nebula is for how stars are born and die inside them.

The Sun and its planets are part of this system, riding along as the whole disk turns. The Milky Way isn’t alone, either: it belongs to a small cluster of galaxies called the Local Group and is slowly heading toward a collision and merger with the neighboring Andromeda galaxy — billions of years from now.

How to see the Milky Way

You really can see our galaxy with your own eyes, and you don’t need any equipment.

Find a dark sky. This is the big one. Light pollution from cities and towns easily drowns out the faint band, so you’ll want to get well away from streetlights.
Pick the right time. The brightest, most dramatic part of the Milky Way — toward the galactic center in the constellation Sagittarius — is best seen on clear summer nights in the Northern Hemisphere, with no Moon in the sky.
Let your eyes adjust. Give yourself 20 to 30 minutes in the dark, away from phone screens, and the soft glowing band will gradually emerge overhead.

Once you can see the band, a pair of stargazing binoculars turns it into a stunning carpet of individual stars and star clusters — a quick, low-cost way to appreciate just how many suns are packed into our galaxy.

FAQ

What is the Milky Way in simple terms?

The Milky Way is the galaxy we live in — a giant, spinning group of hundreds of billions of stars held together by gravity, along with gas, dust and dark matter. Our Sun is one of those stars, located partway out from the center.

How big is the Milky Way?

Its main disk is roughly 100,000 light-years across, meaning even light would take about 100,000 years to cross it. Our Sun sits around 26,000 light-years from the galactic center and takes about 225 million years to orbit it once.

Why is it called the Milky Way?

The name comes from the faint, milky band of light that stretches across a dark night sky. That glow is the combined light of countless distant stars in the galaxy’s crowded disk, seen from our position inside it.

Can you see the Milky Way without a telescope?

Yes. From a dark location far from city lights, on a moonless night, the Milky Way appears as a hazy band across the sky to the naked eye. Binoculars then reveal it as dense fields of individual stars.

Our understanding of the universe evolves as new observations come in. This explainer covers the durable fundamentals and is reviewed periodically.