A faint wash of infrared light captured by NASA’s Spitzer Space Telescope could be a snapshot of the cosmic dawn—the era when millions of the first starry bodies in the universe ignited. These collections of stars, dating from nearly 13.7 billion years ago, would have brought the cosmos out of the dark ages, the murky era that followed the universe’s explosive birth.
Although the stars would have died out billions of years ago, the light they emitted would only now be reaching Earth.
Alexander Kashlinsky of NASA’s Goddard Space Flight Center in Greenbelt, Md., and his colleagues describe the findings in the Nov. 3 Nature. The team analyzed images of part of the constellation Draco taken during a 10-hour observation by Spitzer’s infrared-array camera. The researchers removed the familiar-looking stars and galaxies that crowded the foreground of the images. A faint glow remained, which probably comes from the cosmos’ first stars, the team says.
The expansion of the universe shifts the ultraviolet light from these objects to much longer wavelengths—into the invisible, infrared portion of the spectrum that Spitzer can detect.