At 05:04 UTC (01:04 a.m. EDT) on June 21, the Sun reaches its northernmost point in the sky, which we call the summer solstice. It also means in general it’s the longest day of the year. Since this happens in the middle of the night for us in the United States, it means Thursday and Friday are about the same length; in fact the difference is too small to worry about. For me, in Boulder, Colo., the day is 15 hours and one minute long; compare that to the dead of winter when it’s only about 9.3 hours long!
I’ve written about this about a bazillion times, so check Related Posts below for more info on how this all works. I’ll note that the length of the day depends on your latitude; if you live in Alaska, your days are longer than mine, and if you’re at the Amundsen-Scott South Pole Station, it’s been nighttime for a few weeks now. Living on a great spinning tilted ball is weird, but that’s the hand we’re dealt.
Happy Winter Solstice (2012)! (This is a pretty complete description)
Space Station Solstice
Summer Solstice 2011 (with lots of cool pix of the Sun)
Winter Solstice 2006
… or you can just search the blog for the word “solstice”