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Comment by dreamcompiler | Hacker News Reader

"The researchers were also perplexed by the incredibly small sizes of these systems, only a few hundred light years across, roughly 1,000 times smaller than our own Milky Way. The stars are approximately as numerous as in our own Milky Way galaxy...but contained within a volume 1,000 times smaller than the Milky Way."

If the diameter of a galaxy is one-thousandth, then its volume is one-billionth. They can't both be one-thousandth.

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Many types of galaxies are nearly flat - all stars are approximately orbiting the center of the galaxy in the same plane. Still, that would mean that the "volume" (essentially the area of the disk) is on the order of one millionth the size of the Milky Way if the diamater is one thousandth.

Of course, it's possible that this galaxy is spherical, so your original numbers apply.

I think they mean volume both times. They just forgot to delete bad wording.

I think it's more likely they meant a millionth or a billionth the second time - it's much more common to talk about the size of galaxies in terms of their relative radius than talking about their volume, which you can't directly measure and that's much harder to compute.

The milky way isn't a cube.

Unless it's an almost linear object, its volume is still a power of two or three of its linear dimensions. Many galaxies are quite flat, so their volume could be approximated as X * r^2, though spherical galaxies also exist.

Long thin cylindrical galaxies, where you could see a linear relationship between length and volume, aren't a thing.

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