Summer Solstice 2014 – Welcome To Iced Tea, Mosquitos And BBQ

The first day of summer begins tomorrow June 21 at 5:51 a.m. CDT. It’s also the longest day of the year. Credit: Lyle Anderson

It’s all about the sun. Always has been, always will be. Our lives depend upon the unstoppable nuclear fire that burns in its heart. At no time of year do we feel closer to that fire than at the summer solstice, when the sun reaches its highest point in the sky in the northern hemisphere.

The difference in altitude between the sun at the summer solstice vs. winter is dramatic. Extra height means both longer days and more intense sunlight – the key reasons summer’s so much hotter than winter. Stellarium

At 5:51 a.m. tomorrow morning June 21 – just after sunrise for my little town – summer begins. If you’ve been paying attention, you’ve noticed the sun creeping higher and higher since the time you last shoveled snow. Well, the buck stops at summer. That’s when the sun stands 23.5 degrees above the imaginary circle in the sky called the celestial equator, an extension of Earth’s equator onto the sky.

If we could remove the atmosphere tomorrow, we’d see the solstice sun high in the constellation of Taurus. The sun’s path across the sky and the celestial equator are shown. Stellarium

For anyone living along the equator, its celestial counterpart starts at the eastern horizon, passes directly overhead and then arcs down to the western horizon. In mid-northern latitudes, the celestial equator crosses the southern sky about halfway between the horizon and zenith. Add in 23.5 degrees or about two fists held at arm’s length against the sky, and that’s where the solstice sun stands around 1 p.m. daylight saving time.

23.5 is a familiar number. You’ll recall that’s the tilt of Earth’s axis. No coincidence there. The sun’s yearly swings from its summer peak at 23.5 degrees above the equator to 23.5 degrees below the equator at the winter solstice is merely a reflection of that tilt. In reality, the sun’s not moving at all – it’s the Earth’s doing.

In northern hemisphere summer (left), the north polar axis tilts in the sun’s direction, causing the sun to appear high in the sky and the days to be long. When it points away, it’s winter and the sun rides low in the sky. At the fall and spring equinoxes, the planet is tilted neither toward nor away and day and night are equal. Credit: Tau Olunga

On the summer solstice, Earth’s north polar axis tilts toward the sun, ‘lifting’ it 23.5 degrees above and beyond the equator. Not only is the sun high in the sky, it’s up for many more hours than during the winter. Days reach their maximum length and the sun’s high angle means the energy per unit area it pours over Earth’s surface is more than twice as intense as during the winter. Add it all up and you’ll start feeling … sweaty.

See the seasons unfold before your eyes. This is an animation using monthly global images from the NASA Earth Observatory taken from January to December 2004.

Enjoy the best the sun can bring to the game these next three months. Happy solstice!

6 Responses

  1. Richard Keen

    Welcome to iced tea, mosquitos and BBQ….
    … and to the Milky Way, dew on the finder scope, bats, wet spider webs, distant lightning, the Cat’s Eyes shining through leafy trees, and dawn coming all so quickly, leaving all those late summer goodies on your observing list for another night. Then there’s August’s “heliacal rising” of Capella to remind you how short summer is.

    1. astrobob

      All that and more! And don’t forget. For some of us Capella never sets, all the more reason to enjoy the short season.

      1. Richard Keen

        Bob, good point about Capella. Now we know why your summers are so short!
        I looked up Capella’s declination, 46 degrees N, so it’s circumpolar north of the 44th parallel. You’d have to go down to Rochester to see Capella set, or take the easy route and find a proper hill in Duluth and watch it set from the valley.

        1. astrobob

          On July nights when I walk the road near my home, I’ll catch a glimpse now and again of Capella at lower culmination.

    1. astrobob

      Thanks! I remember this. I was in International Falls on the Minn.-Canada border a few days ago. On the way back south I stopped to look at an outcrop of 2.7 billion year old granite (beautiful pink and white banded material). The black flies were intense at that spot. Just getting in and out of the car I let in a half dozen and spent the next 15 miles trying to smash them before I could get bit. Picture small bloody spots on the windows. Unfortunately I missed one and got nailed!

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