The Distance Scale of the Universe




Last time we looked at a nifty scaling trick to help understand the immense size of the Milky Way. If the Earth-Sun distance shrinks to one inch, the nearest star lies 4.3 miles away and the diameter of our galaxy is 100,000 miles.

Such distances within our galaxy are still a little staggering. Now let’s scale up to understand the size of the universe in terms of a big galaxy. On these terms, the size of the universe becomes much easier to understand…

Imagine the Milky Way and our neighbouring Andromeda galaxy were the size of dinner plates at opposite ends of a table 20 feet long. On this scale, the centre of the nearest major cluster of galaxies, the Virgo Cluster, is about 500 feet away, just a few city blocks over. And the 10,000 galaxies of the Virgo Supercluster, of which the Milky Way is an outlying member, comfortably fill a football stadium.

The Coma Wall of Galaxies lies about 1500 feet from the “plate” of the Milky Way, and the the most distant object visible with a backyard telescope, the quasar 3C273, is about 3.5 miles away. The entire universe on this scale has a radius of 20 miles, about the size of the city of Chicago.

On the scale of galaxies, as you can see, the universe becomes surprisingly intimate.

(Hat tip to the great Timothy Ferris for this analogy, which appears in a similar form in his book Seeing in the Dark).


http://www.oneminuteastronomer.com/5008/distance-scale-universe/