The Universe

How big is it?   How do we find out?

1. Cosmology
2. Relativity

This picture:

  (Click for a larger view)

taken by the Hubble Space Telescope and known as the Hubble Deep Field, is of an area near the handle of the Big Dipper about the size, from our perspective, of the head of a straight pin held at arm's length!

You can see about every type of galaxy, (at least 1,500!)  at distances of tens of millions to billions of light-years from Earth.  There are only a handful of stars from our galaxy in the foreground of this picture.  Every thing else appears to be a galaxy!

Follow links on the Hubble pages to see other Deep Field-type pictures, and updates, like THIS ONE.

Its counterpart in the southern hemisphere, the Hubble Deep Field South, is equally stunning.

So where is our galaxy?  It's part of a cluster of a few galaxies called The Local Group
(look at a 3-D Local Group, see also this from SEDS) that looks something like this  Small Group of Galaxies.

...but only sort of.  Then, our little cluster is part of a bigger one that may look something like this image of a portion of the Virgo Cluster that consists of about 2,000 galaxies, or this of the Coma Cluster...
containing hundreds or thousands of galaxies, or millions in a grouping called a supercluster.
Look at Galaxy Clusters, The Nearest 15,000 Galaxies, The Local Supercluster and Galaxy Cluster Mug Shots to see even more great images.

More Information:

• Is one way to use spectra for distance

• Like the changing sound of a horn, as a car approaches you, then recedes -

• So it is the same with light ...

This is known as:

• Those the farthest from us are moving the fastest!