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Exactly how numerous stars room in space? – MeeSong, Brookline, Massachusetts

Look up in ~ the sky on a clean night, and also you’ll see countless stars – around 6,000 or so.

But that’s only a tiny fraction of all the stars out there. The rest are too much away for united state to view them.


The sun is a star, the closestly one to us – 93 million mile away. Roman inn Studio/Moment via Getty images

The universe, galaxies, stars

Yet astronomers choose me have determined how to calculation the total number of stars in the universe, i beg your pardon is everything that exists.

Scattered throughout the universe are galaxies – swarm of stars, planets, gas and dust bunched together.

Like people, galaxies space diverse. Castle come in various sizes and shapes.

Earth is in the Milky Way, a spiral galaxy; that is stars cluster in spiral arms the swirl approximately the galaxy’s center.

Other galaxies space elliptical – sort of egg-shaped – and some are irregular, with a variety of shapes.


Artist’s ide of a face-on look at the Milky Way. Note the spiral arms. NASA/JPL

from Canyonlands national Park in Utah, a view of a small part of the Milky Way. National Park Service/Emily Ogden

Counting the galaxies

Before calculating the variety of stars in the universe, astronomers first have to calculation the variety of galaxies.

To execute that, lock take an extremely detailed photos of little parts the the sky and count all the galaxies they see in those pictures.

That number is then multiplied through the number of pictures essential to picture the whole sky.

The answer: there are approximately 2,000,000,000,000 galaxies in the cosmos – it is 2 trillion.


15,000 galaxies appear as little dots and blots in this NASA photograph of the night sky. Every galaxy has billions of stars. NASA/ESA/P.Oesch/M.Montes

Counting the stars

Astronomers nothing know precisely how countless stars space in every of those 2 sunshine galaxies. Many are so distant, there’s no way to tell precisely.

But we have the right to make a an excellent guess at the variety of stars in our very own Milky Way. Those stars room diverse, too, and come in a wide variety of sizes and colors.

Our Sun, a white star, is medium-size, medium-weight and medium-hot: 27 million levels Fahrenheit at its center (15 million degrees Celsius).

Bigger, heavier and also hotter stars tend to be blue, favor Vega in the constellation Lyra. Smaller, lighter and dimmer stars room usually red, like Proxima Centauri. Except for the Sun, it’s the the next star to us.

Artist’s ide of a red dwarf star through an exoplanet in orbit. About two-thirds that the stars in the Milky way are red dwarfs. Exoplanet is the surname for people outside our solar system. NASA/ESA/G.Bacon/STScI

An tremendous number

Red, white and also blue stars provide off different quantities of light. By measuring that starlight – specifically, its color and brightness – astronomers can estimate how numerous stars our galaxy holds.

With that method, they found the Milky means has around 100 exchange rate stars – 100,000,000,000.

Now the following step. Making use of the Milky way as our model, we deserve to multiply the variety of stars in a usual galaxy (100 billion) through the variety of galaxies in the universe (2 trillion).

The prize is an absolutely astounding number. There are about 200 billion sunshine stars in the universe. Or, to placed it one more way, 200 sextillion.

That’s 200,000,000,000,000,000,000,000!

The number is therefore big, it’s tough to imagine. But shot this: It’s about 10 time the number of cups the water in all the seas of Earth.

Think about that the following time she looking at the night skies – and also then wonder around what might be continue on the trillions of civilizations orbiting all those stars.

NASA video. Our Milky way galaxy: How large is space?

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