What is the observable universe?

The observable universe is the portion of the universe that we can see from Earth.

The observable universe is estimated to be around 93 billion light-years in diameter. This is because the universe is expanding, and the light from distant objects has taken billions of years to reach us, making them appear further away than they actually are. The observable universe includes all the galaxies, stars, and other celestial objects that we can see with our telescopes. However, there may be much more beyond the observable universe that we cannot see.

One of the most important discoveries in modern cosmology is that the universe is not only expanding, but also accelerating in its expansion. This means that the observable universe is constantly expanding, and the objects within it are moving away from us at increasing speeds. This is known as the Hubble expansion, named after the astronomer Edwin Hubble who first discovered it.

The study of the observable universe has led to many important discoveries in physics and cosmology. By observing the light from distant objects, astronomers can learn about the history of the universe, its composition, and its evolution over time. The observable universe is a vast and fascinating subject of study, and there is still much to be learned about its mysteries.