How do you know this? Have you counted all the stars?

Nevah, nevah, nevah understimate Bravus, Amelia!!!

The key phrase was "known universe"

Indeed. And, that calculation has been made. The boundaries of our universe have been theorized. The most distant observed celestial objects, to date, appear to be near the theoretical limits of this universe.

I didn't count them all, but these guys did: http://edition.cnn.com/2003/TECH/space/07/22/stars.survey/

Mind you, even they say it's possible there are an infinite number.

And while we're on astronomy, here's an exciting find just publicised:

http://www.theage.com.au/articles/2007/04/25/1177459786135.html

It's not an alternative home for humans, because the planet is 5 times as massive as earth, so we'd weigh 5 times as much, and we're not built for that, but it looks as though it has liquid water (or at least the potential for same). Wouldn't it be cool if there were living things there?

An infinite number? They must be exaggerating a little bit. :)

Well, I think they are acknowledging that, although most of our best current models see the universe as closed and expanding and of finite though huge extension, there are other models that see it as of infinite extent. In an infinitely large universe you would presumably have an infinite number of stars.

Mind you, 70 sextillion is not infinity, but you can almost see it from there. ;)

But my point was that we can get lost in how huge the universe is, and not realise that the glass of water in our hand contains 100 times as many particles as the number of stars! The simple stuff is amazing too! It's all amazing!

Here's my rough calculation:

70 sextillion stars is 7 x 10²².

One mole of water contains 6.02 x 10²³ water molecules, weighs 18 grams and fills 18 mls, because water has a density of 1 gram/ml. A cup of water is about 200 ml, or about 11 moles. 11 x 6.02 x 10²³ = 6.7 x 10²⁴... which is roughly 100 times 7 x10²².