Coronal Mass Ejection + STEREO = Mystery?

Gizmodo has an interesting article today about a mysterious object that appears when a coronal mass ejection (CME) reaches Mercury. The site has been updated to show another video taken from another angle as well that seems to show a similar object. Already people are making UFO comments.

A CME is a burst of solar wind, plasma, and magnetic fields that rise above the Sun’s corona and burst out into space. Some are very large, and when they strike Earth, bad things can happen (such as disrupting radio transmissions and damaging satellites and electrical transmission line facilities. On the other hand, they often produce aurorae in areas that don’t normally see the Northern or Southern Lights). Because these bad things can happen, in 2006, the twin Solar TErrestrial RElations Observatories (STEREO) were launched. They orbit the sun, and they are part of a warning system, should a CME be headed in Earth’s direction.

Over a period of 24 hours on December 1, 2011, heliospheric imagers from both STEREO satellites recorded a CME approaching Mercury. Both seem to also show an object near Mercury that is revealed when the CME passes over it. Those who would claim it’s an alien ship note that the object appears to consist of two parallel segments, with other segments joining them. Others, such as Nathan Rich, lead ground system engineer at the United States Naval Research Laboratory in Washington, DC, believes it’s an artifact produced by the way the images are post-processed.

You have to realize that the STEREO imagers aren’t filming like a traditional camera. They are using a variety of sensors to record data, which is then transmitted to Earth, processed, and rendered into a visual presentation. If that data gets screwed up, or if the sensors malfunction, oddities will show up in the visual presentation. Note that the object seems to be about the same length as the diameter of Mercury, and moving in the same direction as the planet. What we are seeing is likely a ghost image of Mercury itself.

I may have the positioning wrong in my head, but it also appears to me that when you compare the video from STEREO A to STEREO B, the object seems to switch sides, from the “sun side” of Mercury to the “dark side” of Mercury. And remember, these videos were taken at the same time, from opposite positions in orbit of the sun. Yet, the size and position of the artifact seems consistently Mercury-like. This would seem to me to bolster the artifact theory.

Of course, if you prefer the UFO theory, check out the comments to the Gizmodo article for references to all the great science fiction spaceships. As for me, I’m comfortable knowing that space is an endlessly fascinating place, full of beauty and mystery, even without little green men spying on us from Mercury.