Astronomy Fun Fact #51
There are about 100 billion stars in the Milky Way galaxy, and there are about 100 billion galaxies in the observable universe (these are rough estimates). That means that there are about 10000000000000000000000 or 10 SEXTILLION stars in the observable universe.
In our own galaxy, astronomers have realized that most stars have planets, which means there are a few sextillion planets out there.
If Earth is the only planet that hosts life, it means that the chances of life occurring in the universe are 1 in 10 sextillion, or 0.00000000000000000001%