Karl Rudolph Powalky (19 June 1817 – 11 July 1881) was a German astronomer known for his computational work on estimating cometary paths and minor planets and for his estimation of the solar parallax at 8.83″.
His achievement was in the calculation of the solar parallax of between 8.832″ and 8.86 arcseconds based on observations made during a transit of Venus in 1769[1] resulting in an estimate of the astronomical unit (AU) which is the mean distance of the Sun from the Earth.
[2] This agreed with the value of 8.86” deduced by Leon Foucault and led to a debate with Le Verrier.
[3] He moved to the United States in 1873 working briefly in the Census Bureau and later at a naval observatory in Washington.
Poor health forced him back to German but he returned and moved to Pennsylvania.