As with weather maps, we are able to determine temperatures, densities, flow speeds and even what the gases are made of. For instance observations of the velocity of gases in the solar atmosphere are made by the Doppler effect - the same principles as that used by police radars to detect speeding motorists or by meteorology Doppler radars to track the movements of clouds and rain. The images and movies above show a large eruption that took place on 14 January. The CDS instrument was fortunate enough to capture an image of the footpoints of the filament just as the eruption was underway. Material moving towards the observer is shown as blue in the velocity map, and material moving away is shown as red.
Gray areas have either zero velocities or too weak signal to detect any velocities.
Although only a preliminary analysis has been performed, the velocity map seems to suggest a rotational movement in the footpoints.