Astronomy Picture of the Day

Explanation: A lone tree stands in a quiet meadow in Guadalajara, Spain, silhouetted against the Cygnus region rising above like flames in the night sky. This deep night skyscape is a composite of exposures that reveals a range of brightness and colour human eyes can't quite see on their own. Spanning over a thousand times the angular size of the full moon, Cygnus sets the sky afire with active star formation where clouds of gas and dust collapse under gravity until nuclear fusion ignites and new stars are born. These stars ionize the surrounding hydrogen gas, causing it to glow crimson, while tendrils of interstellar dust absorb some of that light and cast dark shadows across the sky. Cygnus is a trove of celestial treasures, notably the Veil, Crescent, and Pelican nebulae, as well as Cygnus X-1, the first confirmed black hole. Cygnus continues to yield fresh science, including a new three-dimensional model of the Cygnus Loop made possible by the Chandra X-ray Observatory.