Hubble’s Law
Hubble found that, the more
distant a galaxy, the greater its redshift is, and hence the
faster it is moving away from us…the universe is expanding!
ÞThe
speed of expansion V for a galaxy located
at a distant d away from us is
V = d ´ H0
where,
d = distance in parsec (pc)
H0
= 50~100 [km/sec] / Mpc
H0 is
called the Hubble’s constant, and
1 parsec = 3.26 light-years
Therefore,
once we have determined the value of H0, we can use the recession speed of distance
galaxies to infer their distance using the
formula
d = V /
H0
~ 1.6 billion light-years
