1:28 Solving an Ancient Tablet's Mathematical Mystery Ancient Instruments and Measuring the Stars. . Using the visually identical sizes of the solar and lunar discs, and observations of Earths shadow during lunar eclipses, Hipparchus found a relationship between the lunar and solar distances that enabled him to calculate that the Moons mean distance from Earth is approximately 63 times Earths radius. According to Ptolemy, Hipparchus measured the longitude of Spica and Regulus and other bright stars. Articles from Britannica Encyclopedias for elementary and high school students. Hipparchus used the multiple of this period by a factor of 17, because that interval is also an eclipse period, and is also close to an integer number of years (4,267 moons: 4,573 anomalistic periods: 4,630.53 nodal periods: 4,611.98 lunar orbits: 344.996 years: 344.982 solar orbits: 126,007.003 days: 126,351.985 rotations). For his astronomical work Hipparchus needed a table of trigonometric ratios. Tracking and He may have discussed these things in Per ts kat pltos mniaas ts selns kinses ("On the monthly motion of the Moon in latitude"), a work mentioned in the Suda. This claim is highly exaggerated because it applies modern standards of citation to an ancient author. Knowledge of the rest of his work relies on second-hand reports, especially in the great astronomical compendium the Almagest, written by Ptolemy in the 2nd century ce. Lived c. 210 - c. 295 AD. Hipparchus was the first to show that the stereographic projection is conformal, and that it transforms circles on the sphere that do not pass through the center of projection to circles on the plane. Hipparchus of Nicaea and the Precession of the Equinoxes The Moon would move uniformly (with some mean motion in anomaly) on a secondary circular orbit, called an, For the eccentric model, Hipparchus found for the ratio between the radius of the. Toomer (1980) argued that this must refer to the large total lunar eclipse of 26 November 139BC, when over a clean sea horizon as seen from Rhodes, the Moon was eclipsed in the northwest just after the Sun rose in the southeast. Chapront J., Touze M. Chapront, Francou G. (2002): Duke D.W. (2002). How did Hipparchus discover the wobble of Earth's axis - bartleby