Figure 1 from Hubble 1929 (original paper with open access pdf) has velocity with units of km. Is this just a typo or was there a reason the plot is printed this way?

enter image description here

  • 2
    $\begingroup$ The paper indicates that it should be km/s. Maybe the creator of the graph was not awake when it was made. $\endgroup$
    – LDC3
    Commented Aug 17, 2014 at 2:15

1 Answer 1


It is in fact supposed to be in $\mathrm{\frac{km}{s}}$ (KILOMETRES per second).

I think that whoever authored the paper, probably took it as a random shortcut and assumed anyone reading it would either have read the paper and understand it is supposed to be $\mathrm{\frac{km}{s}}$, or just assume it from the fact it says velocity.

  • $\begingroup$ This can also be confirmed by the single cross mark in Figure 1 at the location described by the sentence "The result, 745 km./sec. for a distance of 1.4 x 10[6] parsecs..." $\endgroup$
    – uhoh
    Commented Dec 31, 2017 at 8:45

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