An Infrared Look Behind Stars

摘要

A quick glance at the night sky reveals that the sky is mostly dark, a profound fact that in itself reveals much about the history of the universe and of the stars within it. Of course, it is not perfectly dark: It glows from Earth's atmosphere and from the zodiacal light of sunlight reflected from dust between the planets, and is peppered with stars because we are viewing the universe from inside the disk of a fairly large galaxy. If we could get outside our Galaxy, the Milky Way, the sky would look much darker but would still glow faintly because the universe is full of galaxies.