This telescopic image shows the glowing red patch in the middle of Orion's sword. This is the famous Orion Nebula, the nearest star-forming region to Earth, 1,500 light years away. The nebula is visible to the unaided eye and is about 20 light years across. Stars are being born within this glowing cloud of dust and hydrogen-rich gas as we watch. In this image, strong ultraviolet radiation from a cluster of young stars hidden in the nebula makes it glow by ionizing the hydrogen and causing it to emit red light.