Please note: Abbreviations used on this page denote common usage unrelated to documenting sources. When documenting sources using MLA style, the months with four or fewer letters, e.g. May, June, and July are not abbreviated, the remaining months Jan., Feb., Mar., Apr., Aug., Sept., Oct., Nov. and Dec. are abbreviated. When documenting sources using APA style, no abbreviations are used, all months are spelled out in full.
Earth's Seasons. Seasons are the result of the tilt of the Earth's axis, from Enchanted Learning.
Why Has Date Changed for Start of Spring? By Joe Rao, Space.com. The first day of spring no longer falls on March 21. Spring season starts one day earlier on March 20 in all time zones in North America. In the years 2008 and 2012, those living in Alaska, Hawaii and the Pacific, Mountain and Central time zones will see spring begin even earlier: on March 19. And in 2016, it will start on March 19 for the entire United States (and most likely for Canada as well).
Domini (in the year of our Lord) after birth of Christ - AD or A.D. (e.g. AD 2008)
before common era - BCE or B.C.E. (same as BC) (e.g. 30 BCE)
common era - CE or C.E. (Christian Era, same as AD) (e.g. 2008 CE)
12-hour clock from Wikipedia, the free encyclopedia. "In the United States ... noon is often called 12:00 p.m. and midnight 12:00 a.m., as at the beginning of a day. ... Strictly speaking, 12 A.M. denotes midnight, and 12 P.M. denotes noon, but there is sufficient confusion over these uses to make it advisable to use 12 noon and 12 midnight where clarity is required."