Helioscope
A helioscope is an instrument used in observing the sun and sunspots.
The helioscope was first used by Benedetto Castelli and refined by Galileo. The method involves projecting an image of the sun onto a white sheet of paper suspended in a darkened room with the use of a telescope.
The first machina helioscopica or helioscope was designed by Christoph Scheiner to assist his sunspot observations.
