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.

Related questions
See all questions in Expansion of the Universe
Impact of this question
3943 views around the world
You can reuse this answer
Creative Commons License