# How do we estimate $10^{23}$ stars in the observable universe?

## 1 Expert Answer

Eric S. answered • 10/27/20

Experienced High School Physical Sciences Teacher and Tutor

The simple answer is statistics. We can measure the number of starts in a finite area and check that same size area in several locations to estimate how many stars are in our galaxy. Once we've done this then we can estimate the total over the whole surface area of the sky. We do something similar with "deep field images" looking at a narrow patch of sky and counting the total number of galaxies in that patch, repeat for a few other locations to check that the number of galaxies is relatively constant (or to find an average if they are not) and then extrapolate to the whole surface area of the sky.

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Arturo O.

The figure of 4,106,234 stars is not correct. A single galaxy contains an average of about 100 to 200 billion stars, and there are many thousands of galaxies.12/19/19