http://wwp.greenwichmeantime.com/longest-day/ The Longest Day Summer Solstice http://wwp.greenwichmeantime.com/longest-day/ http://wwp.greenwichmeantime.com/longest-day/ the new season begins at 12:30 a.m. December 22). http://wwp.greenwichmeantime.com/longest-day/ June 20th