Yes. It's the sun.

One of my very favorite films is "Sunshine" by Danny Boyle, who has directed two of my other favorite films, "Trainspotting" and "28 Days Later."

Thought I'd post a link to the "Sunshine" trailer.  The film is beautiful, sad, and astounding.

http://www.youtube.com/watch?v=YZ2-xR54UDU