ESS55
Prof. Jin-Yi Yu
Seasons and the Elliptical Orbit
qSeasons
      Solstices: mark the longest and shortest days of the years (June 21 and December 21 in the northern hemisphere, the reverse in the southern)
      Equinoxes: the length of night and day become equal in each hemisphere.
qAt the present-day orbit, the winter and summer solstices differ from the aphelion and perihelion by about 13 days.
(from Earth’s Climate: Past and Future)