DO Feature Speaker: Professor Francesca Schironi, U-M Classical Studies

Modern astronomers find the positions of celestial bodies in the sky using coordinate systems, that uniquely identify the position of a celestial object (a planet, a star, a galaxy) through a pair of easily measurable angles. Now a common tool in modern science, such coordinate systems have not been always available in the past; rather, they are the result of a long evolution which started as far back as the Babylonians in first millennium BCE. This talk will outline the history of celestial coordinates from their early beginning in ancient Babylon to their final establishment with Ptolemy (ca. 100-170 CE), with a special focus on the great innovations introduced by one of the greatest astronomers of the ancient world: Hipparchus of Nicaea (ca. 150 BCE).

Talk begins at 7PM at the Detroit Observatory. Tours of the historic Detroit Observatory will be available after the talk, including telescope observing, if weather permits.