# Percent area of the universe is galaxy?

1. May 17, 2012

### sketchd2

%area of the universe is galaxy?

Hi.
I'm trying to determine the approximate percentage of the universe's area that is made up of galaxies for a question I was asked earlier this week. I have been looking everywhere and can not find any information of use. Can someone please help?

2. May 17, 2012

### Chronos

Re: %area of the universe is galaxy?

Try critical density of the universe.

3. May 17, 2012

### sketchd2

Re: %area of the universe is galaxy?

Thank you. That is just what I needed

4. May 17, 2012

### manojr

Re: %area of the universe is galaxy?

Estimated number of galaxies in observable universe is N = 175 X 109, assuming average volume of each 22/7*100000*100000*30000 i.e. v = 9.25 X 1014 cubic light years. Total volume occupied by galaxies = N X V = 1618.75 X 1023 cubic light years.

Compare this with volume of observable universe = 4.1 × 1032 cubic light years.

The Hubble Ultra Deep Field shows 10000 galaxies, but still the photo is mostly black (space).

Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space - Douglas Adams, The Hitchhiker's Guide to the Galaxy