Helioscope

A helioscope is an instrument used in observing the sun and sunspots. The helioscope was first used by Benedetto Castelli (1578-1643) and refined by Galileo (1564–1642). 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 (1575 –1650) to assist his sunspot observations.