We use the beautiful photo above in honor of the upcoming June solstice – June 21 at 5:04 Universal time (12:04 a.m. Central Daylight Time). For the time zones to the west of North America’s Central Time Zone, the June solstice actually happens tonight, on June 20, at 11:04 p.m. MDT or 10:04 p.m. PDT. The photo is from one of our favorite sky photographers, Dan Bush.
No world body has designated an official day to start each new season, and different schools of thought or traditions define the seasons in different ways. In meteorology, for example, summer begins on June 1. And every school child knows that summer starts when the last school bell of the year rings. Yet today is perhaps the most widely recognized day upon which summer begins in the Northern Hemisphere and upon which winter begins on the southern half of Earth’s globe.
The fact is that Earth’s orbit around the sun – and tilt on its axis – have brought us to a place in space where our world’s Northern Hemisphere has its time of greatest daylight. The Northern Hemisphere has its longest day and shortest night. Meanwhile, the June solstice brings the shortest day and longest night south of the equator.
Worldwide map at instant of the June 2013 solstice
Yet even as this astronomical summer begins with the solstice, throughout the world the solstice also represents a “turning” of the year. To many cultures, the solstice can mean a limit or a culmination of something. From around the world, the sun is now setting and rising as far north as it ever does. The solstice marks when the sun reaches its northernmost point for the year. After the June solstice, the sun will begin its subtle shift southward on the sky’s dome again. Thus even in summer’s beginning, we find the seeds of summer’s end.
Bottom line: The June solstice comes on June 21 at 5:04 UT or 12:04 a.m. Central Daylight Time for us in central U.S. There is no official beginning to summer or winter. Yet many will call this the beginning of summer in the Northern Hemisphere, and the beginning of winter in the Southern Hemisphere.