Credit: © The Royal Society
Image number: RS.9603
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“Black drop” effect during the 1769 Transit of Venus
Date
8 June 1769
Creator
Samuel Horsley (1733 - 1806, British) , Clergyman
Object type
Archive reference number
Material
Dimensions
height (painting): 229mm
width (painting): 190mm
width (painting): 190mm
Subject
Content object
Description
Sketch showing the planet Venus at ingress on its passage across the face of the Sun. Detail from a letter by Samuel Horsley, giving an account of the Transit of Venus observed at Oxford, England, using an 18-inch reflecting telescope. Not signed.
Horsley’s textual account described the moment: “When the Planet had been so long upon the Sun’s limb, and so large a part of its circle was plainly entered, that I thought the internal contact was near at hand, I was much astonished to find the shape of the black spot suddenly altered from a large segment of a circle, to what I have attempted to express very rudely by a sketch...where the lower part, which still seemed the segment of a circle, is connected with the Sun’s limb, by a kind of ligament of darkness terminated on each side by right lines...”
The illustration appeared as plate 8 of the published paper “Venus observed upon the Sun at Oxford, June 3, 1769”, by Samuel Horsley, Philosophical Transactions of the Royal Society, vol.59 (1769) pp.183-188.
Horsley’s textual account described the moment: “When the Planet had been so long upon the Sun’s limb, and so large a part of its circle was plainly entered, that I thought the internal contact was near at hand, I was much astonished to find the shape of the black spot suddenly altered from a large segment of a circle, to what I have attempted to express very rudely by a sketch...where the lower part, which still seemed the segment of a circle, is connected with the Sun’s limb, by a kind of ligament of darkness terminated on each side by right lines...”
The illustration appeared as plate 8 of the published paper “Venus observed upon the Sun at Oxford, June 3, 1769”, by Samuel Horsley, Philosophical Transactions of the Royal Society, vol.59 (1769) pp.183-188.
Associated place