Halley’s Comet is certainly history’s most famous comet, but many other comets have unique distinctions. Often new technological advances make things possible that had not been before. This mix timing and technology happened with Donati’s Comet (aka The Great Comet of 1858).
We were now 32 years into the age of photography and almost 10 years beyond the first successful photograph of the moon when Italian astronomer Giovanni Donati observed a comet approaching Earth in June 2, 1858.
By August the comet was visible to the naked eye. By late September the comet was exceptionally bright and close to Earth. Early astrophotographers began training their equipment on the comet. It’s debatable who captured the first image of the comet, but there’s no doubt it was history’s first photographed comet.
The first officially recognized photograph was taken by Brit W. Usherwood. He used a f/2 portrait lens with a seven second exposure on September 27. The following evening, September 28, G.P. Bond at the Harvard College Observatory caught the first image of a comet with a telescope. He used a 15-inch plate and a 6-minute exposure.
The comet reached its brightest on October 10. It was the second brightest comet of the 19th century after The Great Comet of 1811. It was observable for 270 days a record that held until the appearance of Hale-Bopp on 1997. The exact period of the comet is unknown, but estimates at the time were between 1880 and 1950 years. If accurate, it means we won’t see this comet again until late in the fourth millenium.
Usherwood’s photograph has not survived. The above image is another photo taken that same week in September 1858.
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