How do we know Hubble's Constant?

1 Answer
1s2s2p
Mar 9, 2018

#"time"="displacement"/"velocity"#

#"velocity"/"displacement"=1/"time"#

If you were to plot a graph of the distances between Earth and other galaxies and celestial objects beyond our galaxy against their recessional velocity, you'll get an approximate straight line through the constant.

#v=H_0d#

#v_0/d_0=H_0#

The change in recessional velocity over the change in distance is given as the Hubble constant. This is why it is sometimes given as #km# #s^-1 Mpc^-1#, it is #(Deltav)/(Deltad)=(kmcolor(white)(l)s^-1)/(Mpc)#. Mpc is used to simplify the great distances between galaxies.

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