This single frame from a time-lapse sequence was taken on 4 June 1946 by solar physicist Walter Orr Roberts, founder of the National Center for Atmospheric Research, using a Lyot-type solar coronagraph in Climax, Colorado. A solar prominence is an eruption of hot gas from the surface of the sun. This is an early stage of the largest prominence ever documented up to that date and for some years thereafter. Within about an hour, the prominence became nearly as long as the sun's diameter. In a few more hours, it had disappeared completely. The prominence was observed through a very narrow bandpass filter in the red light emitted by hydrogen gas at 6,563 angstroms. It was composed principally of hydrogen gas, with small amounts of helium, calcium, and other gases in the same proportions as they are present in the sun's interior.
