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✦ A Stunning New Map Reveals For The First Time Where Our Galaxy Fits Into The Universe
A Stunning New Map Reveals For The First Time Where Our Galaxy Fits Into The Universe
The entire Milky Way galaxy is a tiny speck on the outskirts of a supercluster of galaxies.
The Earth is the only world for us — for now at least. But our planet is dwarfed by the stars and galaxies that make up the universe.
Even our galaxy is a mere speck in a larger structure, which was just revealed for the first time by a group of scientists who created a map of more than 8,000 galaxies in an effort to understand where they fit in the universe.
The team placed the Milky Way on the outskirts of a massive, previously unknown galaxy supercluster scientists have named Laniakea, from the Hawaiian words for "immeasurable heaven."
The finding, reported in this week's issue of the journal Nature, stems from a new mapping technique that combines not only the distances between more than 8,000 nearby galaxies, but also their motion as the universe expands and galaxies are pulled through space by gravity.
This shows the ways that interconnected webs of galaxies fill the universe, clustering in some areas and leaving others a dark void.
As a video by Nature explains, the universe can be understood as a network of galaxies — a cosmic web. That leaves a void of vast, empty space in some areas, but superclusters of galaxies in other places. These clusters are the largest structures in existence.
The technique enables astronomers for the first time to clearly delineate where one supercluster of galaxies ends and another begins.
The new maps show that the Milky Way galaxy, along with the Virgo cluster and some 100,000 other galaxies, is gravitationally sailing in the same gigantic cosmic pool, named Laniakea.
Most galaxies are pulled toward the heart of a supercluster, a dense center called the great attractor. In Laniakea, even though our galaxy is far, far away on the edge of the system, we're still being pulled by the great attractor's gravity.
The supercluster spans some 520 million light-years in diameter. One light-year is the distance that light, which moves at about 186,000 miles per second (300,000 km/s), travels in one year, or roughly 5.88 trillion miles (9.46 trillion km).
Scientists previously believed the Milky Way galaxy, which is where Earth and the rest of the solar system reside, was part of a cluster measuring about 100 million light-years in diameter. The new study shows that structure is just an appendage of the larger Laniakea.
Bordering Laniakea are the Shapley, Hercules, Coma, and Perseus-Pieces super-clusters, though the far edges of the neighboring galaxy complexes have not yet been determined. Thousands more distance measurements will be needed for that, said astronomer and lead researcher Brent Tully, with the University of Hawaii.
"We haven’t seen the edges of our neighbors, and we haven’t seen far enough to understand what’s causing this full motion of our galaxy,” Tully said in an interview.
Having a clear method for identifying superclusters is expected to help scientists piece together a better idea of how galaxies, including the Milky Way, evolve, astronomer Elmo Tempel, with the Tartu Observatory in Estonia, said in a related Nature commentary.
“Hopefully, this will initiate observational programs to carry out additional direct-distance measurements of galaxies,” Tempel wrote in an email to Reuters.
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