Today’s Wonder of the Day was inspired by Kayla. Kayla Wonders, “How many stars are there?” Thanks for WONDERing with us, Kayla!

Have you ever stared up at the stars in the night sky and wondered how many there are? If so, you're not alone. That question has fascinated astronomers, artists, and dreamers of all ages since the beginning of human history.

Famous astronomer Carl Sagan once estimated that there must be “billions upon billions" of stars in the universe. If you've ever tried to count the stars in the night sky, you may have concluded that it would be impossible to count them all.

Guess what? You'd be absolutely right!

Before we get to the mind-boggling estimates that modern astronomers have made, let's start “small" and get some perspective. We live on planet Earth, which orbits around a star we call the Sun.

The Earth and the Sun, along with several other planets, make up a solar system, which is part of a larger grouping of stars called a "galaxy."

Our particular galaxy is known as the Milky Way. Scientists estimate that there are 200 billion to 400 billion — yes, that's billion with a “b" — stars in the Milky Way galaxy. The Sun is just one of those 200 billion to 400 billion stars.

If that blows your mind, just wait! Our Milky Way galaxy is just one of the many galaxies in our universe.

How many? Believe it or not, astronomers estimate there are 100 billion to 200 billion galaxies in the universe, each of which has hundreds of billions of stars.

If your mind is reeling, that's OK. It's hard for most people to imagine the size of the universe. So how many stars are there? In truth, there are too many to count. Current estimates are just guesses.

Even using our most advanced telescopes and technology, we still cannot see to the ends of our universe. Further complicating things, closer stars that are particularly bright also block our ability to see beyond them in certain directions.

Scientists use observations and data we do have, along with assumptions about our galaxy and the other galaxies in the universe, to estimate the number of stars. Recently, though, some scientists challenged some of the assumptions scientists have been using for years.

The result? Scientists now believe there may be three times more stars than scientists previously estimated.

Why? Astronomers now believe there may be many more red dwarf stars — the most common type of star in the universe — than previously thought.

Based on the latest estimates, astronomers estimate our universe could be the home to 300 sextillion stars. Just how many is that? This many:


That's a 3 with 23 zeroes after it. Any way you look at it, that's a lot of stars. As technology improves and we get even better glimpses at the far corners of the universe, we may eventually find that the number of stars is even greater than anyone could ever imagine!

Wonder What's Next?

Join us in Wonderopolis tomorrow as we exercise our right to free speech!