Vox writes:

We know that the Earth and the solar system are located in the Milky Way galaxy. But how, exactly, does the Milky Way fit in among the billions of other galaxies in the known universe?

In a fascinating new study for Nature, a team of scientists mapped thousands of galaxies in our immediate vicinity, and discovered that the Milky Way is part of a jaw-droppingly massive "supercluster" of galaxies that they named Laniakea.

This structure is much, much, much bigger than astronomers had previously realized. Laniakea contains more than 100,000 galaxies, stretches 500 million light years across, and looks something like this (the Milky Way is just a speck located on one of its fringes on the right):

Say hello to Laniakea, our local supercluster

(Nature Video, based on Tully et al 2014)

It's hard to wrap one's head around how enormous this is. Each of those points of light is an individual galaxy. Each galaxy contains millions, billlions, or even trillions of stars. Oh, and this all is just our little local corner of an even broader universe. There are many other galaxy superclusters out there.

So how did the researchers figure out this structure existed — and how did they distinguish it from other superclusters?

The team of scientists, led by R. Brent Tully of the University of Hawaii, first studied the motion of some 8,000 galaxies in our neighborhood. By doing so, they could map out certain patterns. The universe overall has been expanding ever since the Big Bang. But the team also found that gravity was pulling some galaxies toward each other.

Nice. More at the article.

1700 Reddit comments:

http://reddit.com/r/science/comments/2fij6r/this_is_the_most_detailed_map_yet_of_our_place_in/

Cool video:

http://pandawhale.com/post/50691/laniakea-our-home-supercluster