Light pollution cut humanity’s connection with the stars—but we can restore it The world’s night sky more than doubled in artificial brightness from 2011 to 2022.

To tell which stars are in the background, look at their colors. Stars whose light passes through the absorption nebula will be reddened — their blue light will be preferentially absorbed and ...

This so-called “extragalactic background light” likely dates from roughly 250 million years after the Big Bang. Shortly after the birth of the universe, space was filled with a hot, dense fog ...