A long-awaited device that will help unravel one of the universe’s most compelling mysteries gets ready to see first light.See:The Dark Energy Camera opens its eyes
Unlike the human eye, photographic film and digital cameras can stare at the sky for a long time and store more and more light. By replacing the human eye with cameras, astronomers can detect fainter and more distant objects.
Cameras used for optical astronomy are usually composed of an array of digital chips called charge-coupled devices (CCDs). CCDs convert light into electrons. Each chip is divided into millions of pixels. The electrons generated by the light that hits each pixel are converted to a digital value that a computer can store or display.
In concept, these are the same devices that make up the heart of any home digital camera. However, unlike home cameras that are used to record images of things that are very bright, astronomical CCDs must be souped up in order to detect the tiny amount of light that reaches us from faint and/or distant objects. Much of the light from extremely distant galaxies and supernovae has been redshifted into long-wavelength red and infrared light, which conventional CCDs do not detect very well. See: Dark Energy Survey