Hubble Deep Field Calculations

How many galaxies are there in the Universe?

Download the highest-quality file of the Hubble Deep Field Image (1.45 MB JPEG). Carefully count all of the galaxies that you see in this image. There are two objects in the image with diffraction spikes that are likely stars but every other bright spot is a galaxy.

This picture represents only a very tiny part of the sky. It would take approximately 150,000,000 such images to cover the whole sky! If you multiply the number of galaxies that you counted by 150 million you will have an estimate of the number of galaxies in the universe.

Now do another calculation of your own design using this image. (You could, for example, calculate the ratio of spiral galaxies to elliptical galaxies or find what fraction of galaxies appear to be blue.)

In your report describe the method that you used to count the galaxies and include your estimate of the number of galaxies in the Universe as well as your other calculation.