How Many Stars Are There?

I was just watching the movie A Walk to Remember¹. You know the one... where bad boy Landon falls in love with church girl Jamie. We were at the scene where Landon has a star named after Jamie and asks her to find it in the night sky with her homemade telescope (yeah.., it’s sappy). What if they run out of stars to name, I wondered. Of course I instinctively knew there are more stars than Earthians. But still, how many stars are there?

In 2003, a team at Australian National University² decided to count the stars and came up with 70,000 sextillion, or 70,000 million million million stars… that we could see. That’s 7 followed by 22 zeroes. How did they count them you ask? The simplified explanation is they measured the amount of light emitted by the various galaxies and extrapolated number of stars. And they only sampled part of the Universe and extrapolated again to come up with the whole.

Now fast forward to 2010. It appears there are three (3) times as many stars as previously estimated³. Apparently, there’s something called a dim dwarf star that doesn’t shine brightly enough to be measured. In the original count, the astronomers assumed each galaxy would have about the same proportion of dwarf stars as our own galaxy, the Milky Way. Then a smarty pants astronomer decided to check and found that the number of dim dwarf stars in a galaxy varies widely depending on what type of galaxy it is. As it turns out, some galaxies have hundreds times more low-light-emitting dwarf stars as the Milky Way. Based on the new estimate, there are approximately 210,000 million million million stars. And that’s still only the ones we can see.

So, if you want to have a star named after your Jamie (or your Langdon), having enough stars is not what should concern you. Apparently, none of the companies that sell star names have the authority to do so⁴.

1. IMDB, "A Walk to Remember"
2. CNN, "Stars Survey"
3. NYT, "How Many Stars?"
4. International Astronomical Union, "Buying Star Names"