Comet Donati, or Donati’s Comet, formally designated C/1858 L1 and 1858 VI, is a long-period comet named after the Italian astronomer Giovanni Battista Donati who first observed it on June 2, 1858. It was the fifth comet to be discovered in 1858, and the fourth discovered by Donati (he would discover two more in 1864). After the Great Comet of 1811, it was the most brilliant comet that appeared in the 19th century. It became visible to the naked eye in the both hemispheres between September 1858 and March 1859. It was nearest the Earth on October 10, 1858. The comet has an orbital inclination of 116.9°.
Its gracefully curved tail, which extended almost 40 degrees in the southwestern sky, made a great visual impact and inspired several pictorial (paintings, watercolours, sketches) and poetic (lyrical and satirical) representations, especially in Great Britain and France. Donati’s comet, a true media event of its time, was very much in the public news in September-October of 1858. It was also the first comet to be photographed. The comet was photographed on September 28, 1858, at Harvard College Observatory by George P. Bond, son of William C. Bond, director of the observatory. He made several attempts with increasing exposure times, finally achieving a discernible image.
Abraham Lincoln, then a candidate for a seat in the U.S. Senate, sat up on the porch of his hotel in Jonesboro, Illinois to see “Donti’s Comet” on September 14, 1858, the night before the third of his historic debates with Stephen Douglas over the future of slavery in America, in which Lincoln famously declared “A house divided against itself cannot stand.” Donati’s Comet appears as a streak and star in the early evening sky of a painting by William Dyce, A Recollection of October 5th, 1858.
Due to its astoundingly long elliptical orbit, it is estimated that Donati’s Comet will not be seen passing by Earth again until the 4th millennium.