Astronomy

billion light-years

11 11.25

LIMITS OF THE COSMOS

The far reaches

of space

Using the relative velocities

of galaxies, astronomers in

September 2014 defined the

Laniakea Supercluster (the

region within the outline) as

the one that contains the Milky

Way, the Virgo Supercluster,

and several others. Laniakea

contains more than 100,000

galaxies with a combined mass

of 10^17 Suns in a region of space

520 million light-years across.

R. BRENT TULLY, HELENE COURTOIS, YEHUDA

HOFFMAN, AND DANIEL POMAREDE