When used this way in the present tense, the hay form of haber is used. 1  Hay que saltar. 2  Hay que conocerlo para comprenderlo. 3  HabrÃ¡ que salir a las dos.
So, even though we cannot actually count the number of stars in the galaxy, we can estimate the number of stars in the galaxy as roughly 100 billion (100,000,000,000). It turns out that there are many more stars with mass less than the mass of the Sun than with mass more than the mass of the Sun. So, it all works out right.
A galaxy could average 100 billions stars, and there could be up to 500 billion galaxies in the universe. Even assuming that only 1 out of 10 stars will have planets around and thus be a solar system, the number would thus in the order of 5E21.