20. We Don’t Know Exactly How Many Stars Are There

Have you ever wondered how many stars are in the sky? On a clear night, you can spot hundreds of thousands of teeny tiny lights twinkling in the distance. However, counting stars is not as easy as it might sound, especially when we know there are at least 200 billion in our galaxy. Pinpointing an exact number is almost impossible by any sort of visual detection method, as many stars are too dim for our current equipment or shrouded behind dust. Even if you could count them all, would you really want to? It would take an astronomical amount of time to count each and every single one — and to keep track of the ones you already counted!

The more common method used is to observe the speed of stars’ orbits within the galaxy, which gives an idea of the gravitational tug and therefore allows a rough estimation of the mass of the galaxy. This mass is then divided by the average mass of a star. However, given the number of times we had to say “rough,” “estimate,” and “average,” it should come as no surprise that there is a fair bit of room for error in this calculation. When it comes to counting stars, would you accept a difference of a billion or so? We may never know the real answer to how many stars are in the sky.