APOD's October 17 entry is a stereo anaglyph of Comet 67P/Churyumov-Gerasimenko, constructed from two narrow-angle OSIRIS camera images taken by ESA's Rosetta spacecraft on July 25, 2015, at a distance of 184 kilometers. Put on red/blue glasses and the comet's jagged, double-lobed nucleus lifts off the screen — jets streaming from its active surface near perihelion. The image is the work of Philippe Lamy and his team, who combined the two Rosetta frames into a single red-cyan anaglyph. It's part of a catalog of nearly 1,400 stereo anaglyphs derived from Rosetta's image archive — a project that reprocesses decade-old mission data into something your visual cortex hasn't experienced before. The comet's larger lobe measures roughly 4 kilometers across, connected to a 2.5-kilometer smaller lobe by a narrow neck that gives 67P its rubber-duck silhouette. What makes this worth stopping for isn't the comet itself — 67P has been exhaustively photographed and mapped since Rosetta arrived in 2014. It's the medium. Stereo anaglyphs are one of the oldest tricks in photography, dating to the 1850s, but applying them to spacecraft imagery of an irregular body changes the perceptual stakes. The depth cue isn't decorative; it's the difference between seeing a flat photograph of a boulder field and understanding that you're looking at overhangs, shadow cavities, and jets emerging from specific terrain features. Rosetta's mission ended in September 2016 with a commanded impact onto the comet's surface. The spacecraft is dead. But its data archive lives on, and projects like Lamy's catalog demonstrate that raw mission data has a second life when processed through techniques the original mission plan never prioritized. Nearly 1,400 stereo pairs is not a weekend project — it's a systematic reprocessing campaign. The APOD entry is credited to ESA, Rosetta, MPS, and the OSIRIS instrument team, with the stereo processing by Philippe Lamy and collaborators. Authors and editors for the APOD text are Jerry Bonnell, Cecilia Chirenti, Robert Nemiroff, and Keighley Rockcliffe. This is a small, specific thing done well — archival data, an old perceptual technique, and the result is that a comet 500 million kilometers away briefly becomes a solid object you can rotate in your mind. That's not nothing.
