EXERCISE 1

The photograph on Page 80 is part of the Hubble Deep Field South, one 
of the deepest images ever taken of the sky.  Each blob, large and 
small, on that photo is a galaxy, and the length of one edge of the 
photo is approximately one arcminute.  If the entire sky - Northern 
and Southern hemispheres put together - covers about 41,000 square 
degrees, about how many galaxies are there in the observable universe?