How many planets are there in the universe?

There are currently more than 5,800 known exoplanets outside our solar system. Artist Martin Vargic depicts some of them above. (Image courtesy of Martin Vargic (used with permission))

Space is truly enormous. There are about 100 billion stars in our galaxy, and there could be trillions of galaxies in the universe. (And that trillion number is probably more than you'd expect!) But do we know how many planets orbit those stars?

Astronomers have so far discovered 5,885 planets orbiting other stars (called exoplanets) in the Milky Way. If you add the eight planets in our solar system (not counting the ninth, sorry, Pluto), you'll end up with 5,893 known planets, all of which are in our galaxy. However, counting planets is no easy task, and astronomers are sure there are many more out there that are currently eluding our attention.

“Although we only know about 5,000 planets at this point, we can estimate that there is about one planet for every star,” Mark Popinchalk, an astronomer at the American Museum of Natural History in New York City, told Live Science. “There are 100 billion stars in our galaxy, and there are probably about the same number of planets. We can’t put a number on that.”