Earth sits about 28,000 light-years from the center of the Milky Way galaxy, which itself is one of roughly 100,000 galaxies in a supercluster spanning 500 million light-years. That’s the short version. The full picture of where we are, from our solar system all the way out to the largest structures ever mapped, reveals just how nested our position really is.
Earth’s Full Cosmic Address
Think of your location the way you’d write a mailing address, starting small and zooming out. Earth orbits the Sun in our solar system. The solar system sits inside the Milky Way galaxy. The Milky Way belongs to a small cluster of galaxies called the Local Group. The Local Group is part of a larger collection called the Virgo Supercluster. And the Virgo Supercluster is itself just one piece of an even bigger structure called the Laniakea Supercluster. All of this exists within the observable universe, which extends about 46.5 billion light-years in every direction from Earth.
Each level of that hierarchy is almost incomprehensibly larger than the one before it. The solar system is a speck inside the galaxy. The galaxy is a speck inside the Local Group. And so on. There’s no single “center” to the universe, so Earth doesn’t occupy a special position. But our exact neighborhood at each scale turns out to be surprisingly well mapped.
Where We Sit in the Milky Way
The Milky Way is a barred spiral galaxy roughly 100,000 light-years across, containing around 100 billion stars. The Sun is located about 28,000 light-years from the galactic center, placing us a little more than halfway out from the core. We’re not on one of the galaxy’s major spiral arms but rather in a smaller structure called the Orion Spur, a bridge of stars and gas between the larger Perseus and Sagittarius arms.
This isn’t a fixed position. The Sun orbits the galactic center, completing one full lap every 220 to 230 million years. Astronomers sometimes call this period a “galactic year.” The last time the Sun was at this same point in its orbit, dinosaurs hadn’t yet appeared on Earth. Different stars orbit at different speeds depending on their distance from the center, so the neighborhood around us is constantly reshuffling over millions of years.
The Local Group and Beyond
Zoom out from the Milky Way and you find our galaxy is part of a collection called the Local Group, which contains over 30 galaxies bound together by gravity. Most of these are small dwarf galaxies. The two heavyweights are the Milky Way and the Andromeda Galaxy (also known as M31), which is about 2.3 million light-years away. Andromeda is the most distant object you can see with the naked eye on a dark night, and it’s heading toward us. The two galaxies will merge in roughly 4 to 5 billion years.
The Local Group is a relatively quiet corner. It sits on the outskirts of the Virgo Cluster, a much denser collection of thousands of galaxies. The Virgo Cluster acts as a gravitational anchor for the broader region, pulling surrounding galaxy groups, including ours, in its direction.
The Laniakea Supercluster
For decades, astronomers described our supercluster as the “Virgo Supercluster,” roughly 110 million light-years across. But in 2014, a team of researchers mapped the gravitational flows of tens of thousands of galaxies and discovered that the Virgo Supercluster is just one lobe of something far larger: the Laniakea Supercluster. The name comes from the Hawaiian words for “immeasurable heaven.”
Laniakea spans about 500 million light-years and contains roughly 100,000 galaxies, with a total mass equivalent to 100 million billion Suns. All of these galaxies are flowing toward a region called the Great Attractor, a massive gravitational concentration near the center of Laniakea. The Milky Way, and everything in the Local Group, is being pulled in that direction, though the distances are so vast that the effect plays out over billions of years.
A Void in the Cosmic Web
At the very largest scales, the universe has a structure that’s often compared to Swiss cheese. Galaxies and galaxy clusters are concentrated along filaments and sheets of matter, with enormous mostly empty regions called voids between them. Our position in this web turns out to be surprisingly lonely.
Studies beginning in 2013 identified what’s now called the KBC void, named after the astronomers who characterized it. With a radius of about 1 billion light-years, it’s the largest known void in the universe, roughly seven times bigger than the average void. The Milky Way sits inside it. This means the density of galaxies, stars, and matter in our broader neighborhood is lower than average. At the largest scales, we’re genuinely in the middle of nowhere.
Everything Is Moving
None of these structures are stationary. Earth orbits the Sun. The Sun orbits the galactic center. The Milky Way moves within the Local Group. And the entire Local Group is being pulled toward the Great Attractor while also participating in the overall expansion of the universe.
One way scientists measure all this motion is by looking at the cosmic microwave background, the faint radiation left over from the early universe that fills all of space. That radiation looks very slightly warmer in the direction we’re heading and cooler behind us. Measuring that difference shows that Earth is moving at about 370 kilometers per second (roughly 828,000 miles per hour) relative to this background glow, heading in the direction of the constellation Virgo. You don’t feel it, of course, because everything around you is moving at the same speed. But relative to the oldest light in the universe, we’re covering a staggering amount of ground.