Galaxies drift apart due to cosmic expansion.

Have you ever wondered why galaxies in the universe seem to be moving away from each other? This phenomenon, known as cosmic expansion, is a key concept in astronomy. The universe is not static; instead, it is constantly expanding, causing galaxies to drift apart over vast distances.

One of the most compelling pieces of evidence for cosmic expansion is the observation of redshift in the light emitted by distant galaxies. This redshift occurs because the wavelengths of light from these galaxies are stretched as the universe expands, causing the light to shift towards the red end of the spectrum.

For example, the famous Hubble's Law, formulated by astronomer Edwin Hubble in the 1920s, describes the relationship between the distance of galaxies from Earth and their recessional velocity. This law provides concrete evidence that galaxies are indeed moving away from each other as the universe expands.

Contemplating the vastness of the universe and the constant motion of galaxies can inspire a sense of wonder and curiosity about the mysteries of astronomy. Cosmic expansion is a reminder of the dynamic and ever-changing nature of our universe, prompting us to explore further and deepen our understanding of the cosmos.