— Ch. 1 · Discovery And Naming History —
67P/Churyumov–Gerasimenko.
~5 min read · Ch. 1 of 6
On the 11th of September 1969, a photographic plate exposed at the Alma-Ata Astrophysical Institute captured a faint smudge near the edge of the frame. Klim Ivanovich Churyumov examined this image while working at Kyiv University's Astronomical Observatory. He initially assumed the object was comet Comas Solà because it appeared in that region of the sky. After returning to his home institute, he scrutinized all available plates from the observatory. On the 22nd of October, about one month after the exposure, Churyumov realized the object could not be Comas Sol'. It sat approximately 1.8 degrees off its expected position. Further analysis revealed a faint image of Comas Sol' at its correct location on the same plate. This proved the other object was a distinct body. Svetlana Ivanovna Gerasimenko had taken the original photograph during her shift. The pair named the new discovery after themselves, creating the designation 67P/Churyumov, Gerasimenko.
Physical Structure And Composition
The nucleus measures roughly four kilometers across its longest dimension and two kilometers wide. A smaller lobe connects to a larger one via a narrow neck structure. Scientists determined this shape resulted from a gentle collision between two separate objects moving at low velocity. Each orbit strips away matter as gas and dust evaporate under solar heat. By 2015, estimates suggested a layer averaging three meters thick disappeared per revolution. The total mass reached approximately ten billion tonnes. Rosetta instruments detected sixteen organic compounds within the ice and dust. Four of these substances appeared for the first time on any comet. These included acetamide, acetone, methyl isocyanate, and propionaldehyde. Glycine stood out as the only amino acid found so far. Solid carbon bound itself into very large macromolecular compounds similar to meteoritic material. Free molecular oxygen surrounded the comet in quantities never before seen in cometary comas. This finding challenged existing models suggesting such oxygen should have reacted long ago. Measurements indicated the ratio remained isotropic throughout the coma regardless of distance from the sun.