The black drop effect hampered efforts to obtain a precise value of the astronomical unit during the 1769 transit of Venus observations.
Notes on verification
Multiple independent authoritative sources confirm this fact, including Wikipedia, Sky & Telescope, and academic publications on ResearchGate. The sources provide consistent details about the black drop effect's impact on 1769 transit observations and the inability to achieve precise astronomical unit measurements, with specific mention of timing errors of 30 seconds to 1 minute.
Sources
- 1874 Transit of Venus Expedition to Hawaii (wikipedia)