Return to Scale View
About

How big is the Virgo Supercluster?

950 zettametre!

wiki.history wiki.report
Virgo Supercluster

The Virgo Supercluster, also called the Local Supercluster, is a vast, flattened gathering of galaxy groups and clusters centered on the Virgo Cluster. The Local Group, which includes the Milky Way, lies near one of its edges. The supercluster is roughly 100 million light-years across. A light-year is the distance light travels in one year, about 9.46 trillion kilometers.

Size

A supercluster has no sharp boundary, and even the word "supercluster" has no precise definition, so any size for one is approximate. NASA gives the Local Supercluster a diameter of roughly 100 million light-years. It puts the supercluster's mass at about 1015 times the mass of the Sun, a 1 followed by 15 zeros.

That width fits the supercluster's layout. The Virgo Cluster at its center is about 54 million light-years from Earth, and the Local Group lies near one edge. A supercluster centered on Virgo that reaches out to the Local Group is therefore about twice that distance across.

The supercluster is also flat. In 1982 the astronomer R. Brent Tully found that about 60% of its bright galaxies lie in a thin disk, and the rest in a small number of clouds off the disk. The disk is about six times as long as it is thick, and most of the space above and below it holds almost no bright galaxies.

Size comparisons

  • About 1,000 Milky Ways, each about 100,000 light-years across, would fit side by side across the supercluster.
  • The main body of the Virgo Cluster at its center is about 11 million light-years across, so about nine of them would span the supercluster.
  • The Laniakea Supercluster, which contains it, is about 520 million light-years across, about five times as wide, and has about 100 times the mass.
  • If the Milky Way were shrunk to the size of a basketball, the supercluster would be about 240 meters (790 feet) across. The Virgo Cluster would sit near the middle, about 130 meters (420 feet) from the basketball.

How it was found

Since William and John Herschel made the first large catalogs of nebulae, astronomers have known that faint fuzzy objects crowd a wide band of the northern sky around Virgo. Many of these objects turned out to be galaxies. In the 1950s the astronomer de Vaucouleurs argued that the band was a real structure in space, not a chance line-up. He first called it the "Supergalaxy" and later renamed it the Local Supercluster.

Astronomers debated for decades whether the structure was real. Surveys of the speeds at which thousands of nearby galaxies move away from Earth settled the question in the early 1980s. The speeds reveal each galaxy's approximate distance, and they showed that the galaxies really do lie in a flattened structure.

Part of Laniakea

In 2014, Tully and three colleagues mapped how galaxies move, after subtracting the expansion of the universe. They defined a supercluster as the region inside which galaxies flow toward the same place. By that definition the Milky Way's home is the Laniakea Supercluster, whose name means "immense heaven" in Hawaiian. Laniakea includes the Local Supercluster as it was defined earlier, and Laniakea's galaxies flow toward a region near the Norma and Centaurus clusters called the Great Attractor.

Sources

Evren Ölçeði > Virgo Supercluster

wiki.discussion.title