PHYS 183 Lecture Notes - Lecture 6: The Moons, Ecliptic, Celestial Equator

• School: McGill University
• Department: Physics
• Course: PHYS 183
• Professor: Gilbert Holder

Document Summary

Ea(cid:396)th"s a(cid:454)is tilt with (cid:396)espe(cid:272)t to pla(cid:374)e of its o(cid:396)(cid:271)it is (cid:272)alled ea(cid:396)th"s o(cid:271)li(cid:395)uit(cid:455) Pla(cid:374)e of the ea(cid:396)th"s o(cid:396)(cid:271)it a(cid:396)ou(cid:374)d the su(cid:374) is (cid:272)alled the e(cid:272)lipti(cid:272) pla(cid:374)e. If ea(cid:396)th"s o(cid:271)li(cid:395)uit(cid:455) we(cid:396)e 0 deg(cid:396)ees the(cid:396)e would (cid:271)e (cid:374)o seaso(cid:374)s. Low density of incident rays (northern winter) vs high density of incident rays (southern summer) Answer is c 12 hour days if 0 degrees obliquity. Ecliptic plane at angle 23. 5 degrees with respect to celestial equator. Solstice is when the separation between celestial equator and ecliptic is maximal: occurs twice per year. June 21, december 21: longest, shortest days. The equinox is when the planes intersect: march 21, september 21, night, day both 12 hours. The below pictures attempt to explain and help to make clear how ubiquity affects the length of days and so on. Answer is d because at the solstices, due to rotation, half of the earth would spend 24 hours in dark.