Official NASA Caption: STS105-710-081 (10-22 August 2001) --- One of the astronauts on the aft flight deck of the Space Shuttle Discovery used a 70mm handheld camera to record this image of a thruster firing. The blackness of space surrounds this view of the orbital maneuvering system (OMS) pods during the OMS burn giving the tail of the shuttle a red glow.
Original NASA Source: http://archive.org/details/HSF-photo-sts105-710-081
What are we looking at? You can see, what appears to be, another craft in the background of the photo. With this camera setting, it is illuminated as the astronaut takes the photo of the engines firing on the shuttle. If the shuttle is obviously in the foreground, what's the object behind it?