Gaze skyward on a starry night. The twinkling lights may inspire poetry and spiritual reflection, but even such a dazzling display may be among the more mundane shows in the night sky. The vast reaches of sky that appear vacant to our eyes are actually filled with forms of matter that, when captured by telescopes sensitive to the energy levels at which they radiate, are awe inspiring. They may also reveal the dynamics behind the evolution of the galaxy.
The accompanying image shows one of these "invisible" forms of celestial matter—interstellar gas. These clouds of ionized matter once dominated the galaxy before some of it cooled and coalesced to form stars and planets. The image was collected by the Cerro Tololo Inter-American Observatory in Chile. LAS astronomer Peter McCullough is part of the observatory's international research team that surveyed the entire southern hemisphere. There are more than 1,000 images in the collection, which scientists can manipulate to reveal various properties.