Hubble's Law states that distant galaxies recede from us at a speed proportional to their distance — the further away, the faster they're moving apart from us, which is the key observational evidence behind the expanding universe..
Hubble's Law states that distant galaxies recede from us at a speed proportional to their distance — the further away, the faster they're moving apart from us, which is the key observational evidence behind the expanding universe.
A galaxy is 100 Mpc away, with H0 = 70 km/s/Mpc. Recession Velocity = 70 × 100 = 7,000 km/s.
It describes the observation that galaxies are moving away from us at a speed proportional to their distance — the farther away a galaxy is, the faster it appears to recede.
v = H0 × d, where H0 is the Hubble constant and d is the galaxy's distance.
It's key evidence for the expansion of the universe, since the proportional relationship between distance and recession speed is what you'd expect from space itself stretching uniformly.