Earth sits in a series of nested cosmic structures, each one vastly larger than the last. Starting from our solar system and zooming out, we occupy a specific address: a minor spur of the Milky Way galaxy, inside a small cluster of galaxies, within a supercluster spanning 500 million light-years, all floating inside an observable universe 93 billion light-years across. Here’s what that looks like at every scale.
The Solar System’s Boundaries
Our most immediate cosmic neighborhood is the solar system, which is far larger than most people picture. The familiar planets end at Neptune, roughly 30 times the Earth-Sun distance (a unit called an AU). But the solar system doesn’t stop there. Beyond Neptune lies the Kuiper Belt, a ring of icy objects including Pluto. And far beyond that sits the Oort Cloud, a vast shell of comets whose inner edge begins around 1,000 AU from the Sun and whose outer edge stretches to roughly 100,000 AU. That outer boundary is nearly two light-years from the Sun, almost halfway to the nearest star.
Our Place in the Milky Way
The Sun is one of roughly 100 billion stars in the Milky Way, a barred spiral galaxy about 100,000 light-years across. We’re not at the center and not at the edge. Our solar system sits about 26,000 light-years from the galactic core, in a minor branch called the Orion Spur (sometimes called the Orion Arm). This spur connects two of the galaxy’s major spiral arms, Perseus and Sagittarius, making our location something like a side street between two highways.
At the very center of the Milky Way lies a supermassive black hole, Sagittarius A*, with a mass of about four million suns. Our solar system orbits this center at roughly 220 kilometers per second, completing one full lap every 225 to 250 million years.
The Local Group of Galaxies
The Milky Way isn’t drifting through space alone. It belongs to a collection called the Local Group, which contains over 30 galaxies spread across a diameter of nearly 10 million light-years. Most of these are small dwarf galaxies. The two dominant members are the Milky Way and the Andromeda Galaxy (M31), which sits about 2.3 million light-years away. Andromeda is slightly larger than the Milky Way, and the two are actually moving toward each other, on track to merge in about 4.5 billion years. The third largest member, the Triangulum Galaxy, is a smaller spiral orbiting in the same general neighborhood.
The Virgo Cluster and the Great Attractor
Zooming out further, the Local Group is a suburb of the much larger Virgo Cluster, a dense collection of thousands of galaxies centered about 50 million light-years away. The Virgo Cluster sits at the heart of what was long called the Virgo Supercluster, the structure astronomers once considered our largest cosmic home. But the Local Group occupies the outskirts of this cluster, not the center. We’re a small town on the rural fringe of a metropolitan area.
The Virgo Cluster itself is an outer component of an even larger gravitational concentration called the Great Attractor, an enormous region of mass that pulls galaxies toward it across hundreds of millions of light-years. For decades, astronomers struggled to study it because it lies in a direction partly blocked by the dense star fields of our own galaxy.
Laniakea: Our Supercluster
In 2014, a team of astronomers led by R. Brent Tully redrew our cosmic map by defining a much larger structure: the Laniakea Supercluster. The name comes from Hawaiian, meaning “immense heaven.” Laniakea contains roughly 100,000 large galaxies and spans about 500 million light-years. It includes the Virgo Cluster, the Great Attractor, and many other galaxy clusters, all bound together by shared gravitational flows.
Think of Laniakea as a watershed. Just as rain on one side of a mountain ridge flows into one river system while rain on the other side flows into a different one, galaxies within Laniakea are all being pulled inward toward the Great Attractor region. Galaxies outside Laniakea flow toward different gravitational basins. The Milky Way sits in the outer regions of this supercluster, far from its gravitational center.
The Cosmic Web
At the largest scales, the universe isn’t uniformly filled with galaxies. Instead, matter is arranged in what astronomers call the cosmic web: a network of filaments (long threads of galaxies and dark matter), sheets (flat walls of galaxies), and nodes (dense clusters where filaments intersect). Between these structures lie enormous voids, regions with very few galaxies that can stretch hundreds of millions of light-years across.
The Local Group appears to be located along a filament or sheet in this web, with its orientation aligned along the direction of the surrounding large-scale structure. There’s also evidence that our broader neighborhood sits inside a large underdensity called the KBC Void (named after the researchers Keenan, Barger, and Cowie). This proposed “Local Hole” would be a region where galaxy density is roughly 20 percent lower than average, extending out about a billion light-years in radius. This is still being studied, but if confirmed, it means our corner of the universe is a relatively quiet one.
The Observable Universe
The farthest we can see in any direction is limited by the age of the universe and the speed of light. The observable universe has a radius of about 46.5 billion light-years, making its full diameter approximately 93 billion light-years. That number is larger than the universe’s 13.8-billion-year age because space itself has been expanding the entire time light has been traveling toward us.
Within this sphere, there are an estimated two trillion galaxies. But there’s nothing special about our position in it. The observable universe is centered on Earth only because we’re the ones doing the observing. An alien on a planet 10 billion light-years away would have their own observable universe of the same size, centered on them, overlapping with ours but also seeing regions we never can.
How Fast We’re Moving
Even though you feel stationary, you’re moving through the universe at several compounding speeds. Earth orbits the Sun at about 30 kilometers per second. The Sun orbits the center of the Milky Way at roughly 220 kilometers per second. And the entire Milky Way, along with the Local Group, is moving at about 370 kilometers per second relative to the cosmic microwave background, the faint radiation left over from the Big Bang. That motion carries us in the direction of the constellation Virgo. This speed was measured by detecting a slight temperature difference in the cosmic microwave background: the sky ahead of our motion is fractionally warmer (by about 0.0033 degrees) than the sky behind us.
Mapping the Universe Today
Our understanding of these structures keeps improving. The European Space Agency’s Euclid space telescope began its cosmological survey in February 2024 and released its first batch of calibrated science images in March 2025, covering the largest contiguous area of sky ever observed with an optical and near-infrared space telescope. The mission’s goal is to create the most precise three-dimensional map of the universe across cosmic time, tracking how large-scale structure has evolved and investigating the nature of dark matter and dark energy. Early scientific results published in November 2025 already provided new insights into galaxy formation across billions of years. As more data arrives, our cosmic address will only become more precisely defined.