Comet 1P/Halley in 1835
Hand-drawn sketches can be as valuable as photographs when accompanied by the time and location of the observation. Changes in the shape of the coma from historical records have been used to establish the rotation period of comet nuclei.
These sketches from the 1835 return of Halley's Comet were made by F.W. Bessel, and show detail visible in the inner coma.
Image courtesy NASA/Jet Propulsion Laboratory