What appears to be a cloaked planet sized alien manufactured object appeared near the planet Mercury on 12/01/11 during a coronal mass ejection.
The object only became visible when engulfed within a passing CME and otherwise is invisible.
The official explanation of the object according to Russ Howard, head scientist of the NRL group, and Nathan Rich, lead ground systems engineer, it is simply an artifact left over from the way raw HI-1 telescope data gets processed. Rather than a UFO mother ship parked near Mercury, the bright spot is "where the planet was on the previous day.
This explanation would be acceptable if the object were cylindrical as the planet Mercury is but since it resembles the saucer shape as would be viewed from the side of a disc shaped object it more than likely isn't a ghost image of Mercury.
In relation to the size of Earth this object would be about the size of the entire surface of the Pacific Ocean.
Alien spacecraft or not this object is not natural and has never been viewed (that we know of) before. However, it doe require more scrutiny.