Nobody has any idea how many stars there are in the universe.

This is because we have no way of knowing how far away from Earth we are, and therefore how many stars are visible from our planet. The closest star to us is our sun, and it’s about 150 light years away. If we could travel that distance at the speed of light, it would take us nearly 9 hours to get there. That means if you were standing on Earth and looked up at a star that was that far away, that star would already be half-way across the sky when you saw it!