How Many Stars are There In The Universe?

Look up at the sky on a clear night, and you’ll see thousands of stars – about 10,000 or so. But that’s only a tiny fraction of all the stars out there. The rest are too far away for us to see them. So, how many stars in the universe.

Some estimates peg the Milky Way’s star mass as having 100 billion “solar masses,” or 100 billion times the mass of the sun. Averaging out the types of stars within our galaxy, this would produce an answer of about 100 billion stars in the galaxy. This is subject to change, however, depending on how many stars are bigger and smaller than our own sun. Also, other estimates say the Milky Way could have 200 billion stars or more.

So, How Many Stars are There?

Astronomers don’t know exactly how many stars are in each of those 2 trillion galaxies. Most are so far away that it’s hard to tell for sure.

But we can make good estimates of the number of stars in our own Milky Way. These stars are also diverse and come in a variety of sizes and colors.

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

Larger, heavier, and hotter stars tend to be blue, like Vega in the Lyra constellation. Smaller, brighter, and dimmer stars are usually red, like Proxima Centauri. Apart from the Sun, it is the closest star to us.

How Many Stars are There In The Universe

Red, white, and blue stars emit different amounts of light. By measuring this starlight – specifically its color and brightness – astronomers can estimate how many stars our galaxy contains.

With that method, they discovered the Milky Way has about 100 billion stars – 100,000,000,000.

Now the next step. Using the Milky Way as our model, we can multiply the number of stars in a typical galaxy (100 billion) by the number of galaxies in the universe (2 trillion).

The answer is an absolutely astounding number. There are approximately 200 billion trillion stars in the universe. Or, to put it another way, 200 sextillions.

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

The number is so big, it’s hard to imagine. But try this: It’s about 10 times the number of cups of water in all the oceans of Earth.

Let’s Find Out, How Many Stars in A Galaxy?

According to the Harvard and Smithsonian Center for Astrophysics, it’s easier to count stars when they’re in galaxies because that’s where they tend to cluster. To estimate the number of stars at all, you would need to estimate the number of galaxies and find some sort of average.

Some estimates peg the Milky Way’s star mass as having 100 billion “solar masses,” or 100 billion times the mass of the sun. Averaging out the types of stars within our galaxy, this would produce an answer of about 100 billion stars in the galaxy. This is subject to change, however, depending on how many stars are bigger and smaller than our own sun. Also, other estimates say the Milky Way could have 200 billion stars or more.

However, the number of galaxies is an astonishing number, as shown by some imaging experiments by the Hubble Space Telescope. Several times over the years, the telescope has pointed a detector at a tiny spot in the sky to count galaxies and did the work again after the telescope was upgraded by astronauts during the Shuttle era.

A 1995 exposure of a small spot in Ursa Major revealed about 3,000 faint galaxies. In 2003-4, using upgraded instruments, scientists looked at a smaller spot in the constellation Fornax and found 10,000 galaxies. An even more detailed investigation in Fornax in 2012, with even better instruments, showed about 5,500 galaxies.

Kornreich used a very rough estimate of 10 trillion galaxies in the universe. Multiplying that by the Milky Way’s estimated 100 billion stars results in a large number indeed: 1,000,000,000,000,000,000,000,000 stars, or a “1” with 24 zeros after it (1 septillion in the American numbering system; 1 quadrillion in the European system). Kornreich emphasized that the number is likely a gross underestimation, as more detailed looks at the universe will show even more galaxies.