They deduced that prominences were part of the sun , because the moon was seen to cover and uncover them as it moved in front of the sun .
Among the other observers were British astronomers Robert Grant and William Swan , and Austrian astronomer Karl Ludwig von Littrow .
astronomers deduced that prominences were part of the sun , because the moon was seen to cover and uncover them as it moved in front of the sun .
Among the other observers were British astronomers Robert Grant and William Swan , and Austrian astronomer Karl Ludwig von Littrow .