The nature of planetary nebulae remained unknown until the first spectroscopic observations were made in the mid-19th century. Using a prism to disperse their light, William Huggins was one of the earliest astronomers to study the optical spectra of astronomical objects.
The nature of planetary nebulae remained unknown until the first spectroscopic observations were made in the mid-19th century. Using a prism to disperse their light William Huggins was one of the earliest astronomers to stud,y the optical spectra of astronomical objects.