Official NASA Caption: S120-E-006876 (26 Oct. 2007) --- Astronaut Scott Parazynski, STS-120 mission specialist, is pictured in the shutte's cargo bay during the first of five scheduled sessions of extravehicular activity to perform work on the International Space Station while it is visited by the Space Shuttle Discovery. Node 2, also known as Harmony, joined the growing station complex, thanks to the work of the two spacewalkers in conjunction with that of their crewmates who remained in the shirt sleeve environment of the two spacecraft.
What are we looking at? You can see a unidentified object in the background of the photograph released during the STS-120 mission. With the billions of stars in the sky, and none show during most photos in space, this could theoretically be ruled out. What could the object be?
High resolution photo is below for download.