Somewhere in the Universe is a small blue planet,
the third rock from a star called the Sun,
just one of billions of stars in a spiral galaxy known as the Milky Way.
But where in the Universe is the Milky Way?
A team of scientists gathered data on more than 8,000 of the galaxies that surround us.
They mapped each galaxy's position and movement in space.
And for the first time, they've shown that the Milky Way is part of a much larger system of galaxies,
a supercluster that they have named Laniakea.
The Milky Way is nested in the furthest reaches of this structure, on the outskirts.
The entire Universe can be seen as an intricate network of galaxies, a cosmic web.
Some areas are almost empty, dark voids.
Others are densely packed with galaxies in regions known as superclusters.
Superclusters are the biggest structures found in the Universe,
but scientists have struggled to define where one ends and another begins.
To map our home supercluster, a team led by Brent Tully at the University of Hawaii
studied the motions of the galaxies around us in unprecedented detail.
Even though the entire Universe is expanding rapidly, gravity is also at work, pulling against this acceleration.
By discounting cosmic expansion, the team worked out which galaxies are being pulled towards us
(shown in blue) and which are being pulled away (shown in red).
This enabled them to create a map of cosmic flows, the paths that galaxies migrate along,
tugged at a tiny pace by the force of gravity.
Using this motion, they came up with a new way to map the distribution of matter in the Universe.
Delving into our home supercluster, you can see that most galaxies are being pulled towards a dense centre.
This is known as the Great Attractor.
Our galaxy is among those sliding towards this patch of space
which dominates our region of the Universe.
Let's take a different view.
Each circle represents a galaxy.
Again, we can see most galaxies being pulled towards the Great Attractor in the direction of the arrows.
Between the Great Attractor and us, the Milky Way, there's a relatively empty area, a blue void,
and next to us is Virgo, a large and dense cluster
whose large galaxies have been observed from Earth for centuries.
Until now, astronomers grouped us, the Milky Way and its surrounding galaxies,
with Virgo and nearly 100 other clusters in a supercluster
that stretches 100,000,000 lightyears across.
But using this new technique, we can see that this is just the tip of the iceberg.
This cluster of clusters is merely an appendage of a much larger supercluster,
more than 100 times bigger and more massive.
But how did the team know how to redraw the boundaries of this cosmic map?
Here's our supercluster (in black) and a neighbouring structure, Perseus-Pisces (in red).
Scientists defined the boundary as the points where the flows of galaxies diverge,
like water dividing at a watershed.
This is where neighbouring structures shear apart.
This is the first clear definition of a supercluster.
Laniakea means 'immeasurable heaven' in Hawaiian,
a fitting name for the vast community of galaxies that we are a part of.
So, now we know that on the edge of a supercluster called Laniakea,
in a galaxy called the Milky Way, around a star we call the Sun,
there is a small blue planet, our home.