The Whole World In Your Hand

Could you understand the stars and planets by using a devise small enough to fit on your desk? Before telescope, globes and modern planetariums, astronomers and mathematicians wanted tools to help them figure out celestial objects’ locations and predict their motions. Luckily, the ancient Greek invented the armillary sphere, an object that demonstrated the motions of celestial objects through the sky. (This predates the idea that the Earth and planets move around the Sun. Later, the design of these spheres changed so that the Sun-and not the Earth- was positioned in the center. People still own armillary sphere today, but they are mostly used for decoration.