What does Hubble's Law state?

Hubble's Law describes the observed relationship between the distance of galaxies and their recessional velocity, which is often measured through redshift. The law states that the further away a galaxy is, the faster it appears to be moving away from us, indicating that the universe is expanding. This is quantified by stating that the velocity of recession of a galaxy is proportional to its distance from us.

This relationship has been observed through meticulous measurements of distant galaxies and is a foundational aspect of modern cosmology. It provides strong evidence that the universe is not static, but rather dynamic and expanding, which is a key concept in our understanding of the universe's history.

The other options do not accurately reflect Hubble's findings; for instance, the idea that galaxies are moving toward Earth contradicts the evidence for expansion, and the notion of a static universe goes against the observations that led to the formulation of Hubble's Law. Similarly, brightness does not have a direct correlation with distance in the context of Hubble’s observations. The law fundamentally reshaped our understanding of the cosmos and emphasized the large-scale structure of the universe.