The oldest known light from space is known as the cosmic microwave background radiation (CMB). The CMB is a faint glow of radiation that permeates the entire universe and is considered the afterglow of the Big Bang, which occurred approximately 13.8 billion years ago.
The CMB was first discovered in 1965 by Arno Penzias and Robert Wilson, who were conducting experiments with a radio antenna and detected a low-level, uniform radio signal coming from all directions in the sky. This signal turned out to be the CMB, which had cooled and stretched over time to become microwave radiation.
The CMB provides important insights into the early universe. It is often referred to as the "baby picture" of the universe, as it allows scientists to study the universe as it existed only about 380,000 years after the Big Bang. It provides valuable information about the structure, composition, and evolution of the universe.
Other examples of ancient light from space include:
Distant Galaxies: Astronomers can observe light that has traveled billions of light-years to reach us. This allows them to see galaxies as they appeared in the early universe, providing a glimpse into the past.
Quasars: Quasars are extremely bright and distant objects powered by supermassive black holes. The light from quasars takes billions of years to reach us, allowing astronomers to study some of the most ancient and energetic phenomena in the universe.
Supernovae: Supernovae are explosive events that mark the end of a massive star's life. By observing the light from distant supernovae, scientists can study the properties of the universe at the time the light was emitted.
These examples, along with the cosmic microwave background radiation, offer valuable insights into the early universe and help us understand its origins and evolution.