If you’ve been waiting for the chance to get more done during the day, Sunday was your day, but only by a fraction of a second. Like a giant timepiece, Earth and sun are configured for the summer solstice once again. This year it happens June 21, the longest day of the year in the Northern Hemisphere. The sun will be up a fraction of a second longer than the day prior or the day after. (The length of the full day, including night, does not change, of course.) Our planet is tilted 23.5 degrees on its spin axis. On June 21 this year (some years it’s June 20), the North Pole is pointing toward the sun as much as is possible.
On or around June 21 each year, the rays of the sun is perpendicular to the Tropic of Cancer at 23°30′ North latitude. This day is the summer solstice in the Northern Hemisphere.
On this day, the earth’s “circle of illumination” will be from the Arctic Circle on the far side of the earth (in relation to the sun) to the Antarctic Circle on the near side of the earth. The equator receives twelve hours of daylight, there’s 24 hours of daylight at the North Pole and areas north of 66°30′ N, and there’s 24 hours of darkness at the South Pole and areas south of 66°30′ S.June 20-21 is start of summer in the Northern Hemisphere but simultaneously the start of winter in the Southern Hemisphere. It’s also the longest day of sunlight for places in the Northern Hemisphere and the shortest day for cities south of the equator.