This story is part of our Cosmic Perspective series, in which we confront the staggering vastness of the cosmos and our place in it. Read the rest of the series here.
This map shows the circle of the cosmos that surrounds us, extending to a distance of 200 million light years. At this scale, space is comprised of clusters of galaxies and voids, the latter being areas with relatively few galaxies. The Milky Way, at the centre, is part of the Local Group of galaxies, with the Virgo cluster our nearest neighbour.
Majestic spiral
The Milky Way’s spiral structure is dominated by two main arms called Scutum-Centaurus and Perseus. It also features a dense region known as the central bar. Our solar system lies on a more modest structure called the Orion spur.
However tangled the question of our metaphorical place in the universe, we can use astronomy to grasp Earth’s physical location.
Earth orbits the sun at a distance of 150 million kilometres and the sun orbits the centre of the Milky Way. Specifically, we are in the Orion arm, around 26,500 light years from the centre.
The Milky Way resides in the Local Group of galaxies. About 2.5 million light years away is our closest neighbouring galaxy, Andromeda, the largest galaxy in the Local Group. Right now, we are hurtling towards Andromeda at more than 100 kilometres per second; in about 4 billion years, the two galaxies will collide.
The Local Group
That will shake up the Local Group, but it will be barely a blip on the radar of the wider cosmic neighbourhood.…