Hubble's Law reveals one of the most profound discoveries in cosmology: the universe is expanding. Formulated by Edwin Hubble in 1929, this fundamental relationship states that galaxies are receding from us at velocities proportional to their distances, expressed as v = H₀ × d, where H₀ is the Hubble constant (approximately 70 km/s per megaparsec).</p><p>Imagine the universe as a rising loaf of raisin bread—as the dough expands, raisins farther apart move away from each other faster than nearby ones. Similarly, a galaxy 100 million light-years away recedes at roughly 7,000 km/s, while one at 200 million light-years races away at 14,000 km/s.</p><p>Hubble discovered this pattern by measuring redshift—the stretching of light waves from receding objects—in distant galaxies. The Andromeda Galaxy, our nearest major neighbor at 2.5 million light-years, actually approaches us at 110 km/s because local gravitational forces overcome cosmic expansion. However, the distant Virgo Cluster, 54 million light-years away, recedes at about 1,200 km/s.</p><p>This law provides crucial evidence for the Big Bang theory and allows astronomers to calculate the universe's age (approximately 13.8 billion years). Modern space telescopes continue refining H₀, helping us understand dark energy's role in accelerating cosmic expansion.