Editing Hipparchus (section)

===Orbit of the Sun===
Before Hipparchus, astronomers knew that the lengths of the [[season]]s are not equal. Hipparchus made observations of equinox and solstice, and according to Ptolemy (''Almagest'' III.4) determined that spring (from spring equinox to summer solstice) lasted 94{{frac|1|2}} days, and summer (from summer solstice to autumn equinox) {{frac|92|1|2}} days. This is inconsistent with a premise of the Sun moving around the Earth in a circle at uniform speed. Hipparchus's solution was to place the Earth not at the center of the Sun's motion, but at some distance from the center. This model described the apparent motion of the Sun fairly well. It is known today that the [[planet]]s, including the Earth, move in approximate [[ellipse]]s around the Sun, but this was not discovered until [[Johannes Kepler]] published his first two laws of planetary motion in 1609. The value for the [[eccentricity (orbit)|eccentricity]] attributed to Hipparchus by Ptolemy is that the offset is {{frac|1|24}} of the radius of the orbit (which is a little too large), and the direction of the [[apogee]] would be at longitude 65.5° from the [[March equinox|vernal equinox]]. Hipparchus may also have used other sets of observations, which would lead to different values. One of his two eclipse trios' solar longitudes are consistent with his having initially adopted inaccurate lengths for spring and summer of {{frac|95|3|4}} and {{frac|91|1|4}} days.{{sfn |Thurston |2002 |loc=p. 67, note 16}}{{failed verification|date=September 2023}} His other triplet of solar positions is consistent with {{frac|94|1|4}} and {{frac|92|1|2}} days,{{sfn |Jones |2001}}{{sfn |Thurston |2002 |loc=note 14}}{{failed verification|date=September 2023}} an improvement on the results ({{frac|94|1|2}} and {{frac|92|1|2}} days) attributed to Hipparchus by Ptolemy. Ptolemy made no change three centuries later, and expressed lengths for the autumn and winter seasons which were already implicit (as shown, e.g., by A. [[Aaboe]]).{{citation needed|date=April 2023}}