Astronomy Picture of the Day . ... 30.07.1997 . ... Credit: P. Challis ( CfA ), Whipple Obs. , 1.2 m Telescope Explanation: What lights up this castle of star formation? The familiar Eagle Nebula glows much like a neon sign , but in many colors at once. The above photograph is a composite of three of these glowing gas colors. In particular the glowing red Sulfur gas of the nebula nicely outlines some of the denser star forming knots . ... U. Based on Astronomy Picture Of the Day ...