Bible Encyclopedias
Black Drop

1911 Encyclopedia Britannica

In astronomy, an apparent distortion of the planet Mercury or Venus at the time of internal contact with the limb of the sun at the beginning or end of a transit. It has been in the past a source of much perplexity to observers of transits, but is now understood to be a result of irradiation, produced by the atmosphere or by the aberration of the telescope.

Bibliography Information
Chisholm, Hugh, General Editor. Entry for 'Black Drop'. 1911 Encyclopedia Britanica. https://www.studylight.org/​encyclopedias/​eng/​bri/​b/black-drop.html. 1910.