Why we nonetheless don’t know what number of stars are within the Milky Approach | by Ethan Siegel | Begins With A Bang! | Apr, 2025

We perceive many issues about our Universe, and our residence inside it, extraordinarily nicely. The variety of stars within the Milky Approach isn’t amongst them.

It’s as easy and easy a query about our cosmic residence as you may think about: what number of stars are in our Milky Approach? Whereas there’s an unlimited quantity that we find out about our Universe with a major quantity of confidence — what kinds of matter and power are current inside it, how a lot of every species we’ve, how briskly the Universe is increasing, how a lot time has elapsed for the reason that scorching Huge Bang, what number of galaxies are inside it, and so on. — studying some essential details about our own residence inside the cosmos has been exceedingly troublesome. Though we stay inside the Milky Approach, there’s an incredible quantity of details about it that we merely wrestle to find out.

Our greatest image of our galaxy, for instance, requires an in depth quantity of guesswork, because the galactic aircraft of the Milky Approach is closely dust-obscured, making it obscure the construction of the far facet of our galaxy. We find out about our central budge and bar, in addition to our distance to the galactic heart and its supermassive black gap, however we wrestle with the form, density, and thickness of our galaxy’s spiral arms and different properties of our galactic disk.

However maybe the best, and easiest, proven fact that’s nonetheless unknown concerning the Milky Approach is what number of stars are current inside it. Whereas essentially the most generally cited determine is round 200 billion stars, some sources nonetheless cite a decrease worth of as little as 100 billion, whereas different sources favor the next worth: maybe as nice as 400 billion. How can we all know so little about our personal galaxy, given our intensive information of the Universe? There are main scientific causes for our ignorance, and our uncertainty displays the value we pay for being scientifically sincere about what we’ve but to determine about our Universe.

Above, what you see will not be the Milky Approach, however relatively a galaxy that shares many options in frequent with…