Observable Universe

Observable Universe
This diagram shows why we only see part of the entire universe. As time passes, this volume grows, meaning that light from more distant galaxies
reaches us. The farthest galaxies we see (inset) are as they were within a few hundred million years after the Big Bang. These galaxies, formed
at the same time as the Milky Way, appear young because the light from their beginnings is just now reaching us. While the light from the most
distant galaxies we see was traveling toward us, the universe has been growing. Therefore, objects that appear 13 billion ly away from
us are actually about 3 times farther away today. Put another way, if we could see it all as it is today, rather than as it was when photons from
distant objects started their journeys, the visible universe would be nearly 46 billion ly in radius. (Inset) This image shows some of
the most distant galaxies we have seen.