The Light We See
The visible light we see with our eyes is a fraction of the light in the universe. Most Earth-based telescopes observe primarily in visible-light wavelengths. We also use space-based instruments like the Hubble Space Telescope to rise above Earth's interfering atmosphere.
If we could stare into space continuously for ten days, we would see some of the most distant galaxies in the cosmos. This is what the Hubble Space Telescope did in 1996.
The resulting visible-light Hubble Deep Field image (left) is stuffed with galaxies. Many are so far away that they appear as they did when the universe was only a billion years old.