What Did NASA Cameras Capture Near Mercury? A UFO? Mystery Planet?

Stargazers have been debating in slack-jawed amazement after the release of footage captured by the STEREO A satellite.  What looks just like a big blob of red to me has been described in the YouTube video below as a 'cloaked alien craft.'  Others speculate it's a 'ghost image' of Mercury of a blip on the satellite.

Whatever the red smudge turns out to be, it makes for some interesting stargazing.