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Comment by tromp | Hacker News Reader

> and its mass is estimated to be 650 billion solar masses

One could also say this new galaxy's mass is estimated to be 0.565 Milky Way masses, but for some reason that unit of mass seems not to have caught on...

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Isn't there a lot of uncertainty about the mass of the milky way? I think if you are going to use something as a unit you really need an accurate figure.

There is indeed lots of uncertainty, and all Milky Way mass estimates are model dependent. Also, the ~10^12 solar mass figure referred to above is an estimate of the total galaxy + dark matter halo mass. Stellar or baryonic mass estimates are closer to ~6 x 10^10 solar masses. I'm using "~" to mean uncertainty to within a factor of 2 or so.

Stacy McGough wrote about this topic recently wrt the third Gaia data release: https://tritonstation.com/2023/09/19/recent-developments-con...

As long as we don’t measure length in football fields I won’t get triggered.

Proposal to Rename the Milky Way Galaxy to “the Football Field”

How would you go about doing this - just out of curiosity.

> How would you go about doing this - just out of curiosity.

Take the length and divide it by the length of a football field?

The first step would be defining what football means.

That would keep us entertained for many dog years.

How many kiloyards in width is this new galaxy?

Me neither, as I prefer washing machines over football fields.

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