Lost at sea in the middle of a night full of stars? Your best hope for finding your way is to use one of tools explored in this section to measure your angle relative to the stars. In this section we explore several different instruments: the astrolabe, cometarium, cross-staff, orrery, and a subgroup of instruments classified as sextants, octants, and quadrants. Click on one of the images below to get started, or use the bar up above to go back to check out the other categories.