Webb's Vision
Imagine a universe of total, perfect darkness.

The glow of the Big Bang has faded away, leaving a blackness unbroken by even a single star. But in this void matter is gathering, collecting. Eventually, it will become dense enough to give birth to the first stars -- the first light in the universe.

This mysterious period in the universe’s evolution, after matter began to form structure but before the evolution of the galaxies and stars we see today, is called "the Dark Age."

The James Webb Space Telescope will gaze back to the end period of the Dark Age, to the time when the first stars and galaxies began to form.

Webb will study ultraviolet and visible light from this early time. Such emissions have been stretched — or redshifted — by the expansion of the universe until they can only be seen in infrared wavelengths. The telescope will use technology similar to that of infrared-sensitive night-vision cameras to make its observations.