Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Hubble's Law describes the observation that galaxies are receding from us at velocities proportional to their distance. This relationship is a cornerstone in understanding the expanding universe and supports the Big Bang theory.
5 Must Know Facts For Your Next Test
Hubble's Law is mathematically expressed as v = H₀d, where v is the galaxy's recessional velocity, d is its distance from Earth, and H₀ is the Hubble constant.
The discovery of Hubble's Law was made by Edwin Hubble in 1929 using observations of distant galaxies.
Hubble's Law provides evidence for an expanding universe, which implies that the universe had a beginning—often associated with the Big Bang.
The value of the Hubble constant (H₀) has been refined over time and is crucial for estimating the age and size of the universe.
Redshift measurements of galaxies are used to determine their velocities, which are critical data points for applying Hubble's Law.
Redshift refers to the phenomenon where light or other electromagnetic radiation from an object increases in wavelength due to its motion away from the observer.
The prevailing cosmological model explaining the origin of the observable universe as starting from a singularity approximately 13.8 billion years ago.