Final answer:
Hubble's Law describes the expansion of the universe, with the Hubble's Constant indicating the rate at which galaxies recede from us based on their distance. The current value of Hubble's Constant is estimated between 21 to 23 km/s/Mly, signifying that galaxies recede faster as they are farther away, and it changes over time.
Step-by-step explanation:
Hubble's Law describes the relationship between the distance to a galaxy and its recessional velocity due to the expansion of the universe. The formula v = H0 × d represents this, where 'v' is the velocity at which a galaxy moves away from us, 'H0' (Hubble's constant) is the proportionality constant, and 'd' is the galaxy's distance from Earth. Hubble's Constant is estimated to be between 21 to 23 kilometers per second per million light-years, indicating that for every million light-years away a galaxy is, it recedes an additional 21 to 23 kilometers per second. Although often referred to as a constant, Hubble's constant does change with time; the current estimated value is reconsidered as the expansion rate of the universe at our current point in time.