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You live inside it

What Is the Milky Way?

That milky band across the sky is our own galaxy, seen edge-on from within.

The Milky Way One of 200 billion stars— ours
We are not looking at it. We are looking through it.

  1. Step 1 of 5

    Stars come in enormous groups.

    Our galaxy's starsabout 200billionPeople on Earth8 billionStars you can see by eyeabout 2,500

    Stars are not scattered evenly through space. They gather into galaxies — vast whirlpools of hundreds of billions of stars held together by gravity.

  2. Step 2 of 5

    We are in one, far out from the middle.

    Bulge — crowded centreSpiral arms — where weliveThe Sun: 26,000 lightyears outHalo — sparse old stars

    The Sun sits roughly 26,000 light years from the galactic centre, out in one of the spiral arms. We are suburbanites.

  3. Step 3 of 5

    The galaxy is a flat disc, not a ball.

    Looking through the disc Millions of stars, allin a lineLooking out of the disc Mostly empty dark sky

    It is about 100,000 light years across but only about 1,000 light years thick — the proportions of a dinner plate, not an orange.

  4. Step 4 of 5

    So we see it as a band.

    1 You, inside thedisc2 Look along theplane3 A milky bandappears

    Look along the flat plane of the disc and your line of sight crosses countless stars, which blur together into a milky stripe. Look up out of the disc and you see far fewer.

  5. Step 5 of 5

    Galileo settled what the band was made of.

    Through a telescope The smear is countlessstars

    For thousands of years it was a mystery smear. In 1610 Galileo pointed a telescope at it and saw the smear break apart into individual stars.

    We are also moving — the Sun takes about 230 million years to go once around the galaxy.

The short version

The Milky Way is our own flat, spiral galaxy, seen edge-on from a seat inside it.

Try it yourself

Stand in the middle of a crowded room and look sideways — people blur into a wall. Look at the ceiling and you see nobody. Same effect.

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