This is an image of Mercury's tail obtained from combining a full day of data from a camera aboard the STEREO-A spacecraft. The reflected sunlight off the planet's surface results in a type of over-exposure that causes Mercury to appear much larger than its actual size. The tail-like structure extending anti-sunward from the planet is visible over several days and spans an angular size exceeding that of a full Moon in the night sky.(Credit: Image courtesy of Boston University’s Center for Space Physics)
Back in 2008 Comet Al and I were trying to confirm a comet position in images from STEREO A. I pointed out the nice bright comet moving across the STEREO image field and Comet Al said, "That's not a comet, that's Mercury!". We exchanged the internet equivalent of startled looks.
The feeling on the Stereohunter list was that it was an artefact, but I remembered an article on sodium emission from Mercury, and went to track down the group and ask them what they though our tail might be.
So began a saga that cumulated in the paper "Observations of Mercury’s Escaping Sodium Atmosphere by the STEREO Spacecraft" by Carl Schmidt, Jeffrey Baumgardner, Michael Mendillo, Christopher Davis and Ian Musgrave being read at the European Planetary Science Congress today. This paper was the subject of a press release, and has spread wide into the internet (Science Daily, Space.com, and SpaceInfo are just a few examples).
I must say I'm mildly chuffed to be mentioned in press releases, I'm more chuffed that I was included in the paper. I've got 40 peer-reviewed papers of my own in the field of biomedical science (ask me about Maitotoxin!), some of which I am very proud of, so I'm no stranger to being published.
But this is the first time my amateur efforts have made a contribution to advancing astronomical research, my beloved hobby. Of course, the others did all the really hard work of ground observations and calibrating the Stereo images, so my contribution needs to be put into perspective, but still.... ther's that warm inner glow that in a small way I made a difference.
My blog posts on the tails (with nice images and animations and a bit more background), can be found here.