23 January
1930: On 23 January 1930, Clyde Tombaugh photographed the planet Pluto.
Tombaugh had first photographed Pluto, while searching for the planet in the Delta Geminorum region, on 21 January 1930. Strong winds on the night moved the telescope and blurred the image.
He made further exposures on 23 January and 29 January. On checking them on 18 February 1930, the planet Pluto was seen on these photographic plates.
