21 June 2012

June Solstice

Solstice Skies Around the World

The rolling Planets, and the glorious Sun,
Still keep that order which they first begun;
But Man! once innocent -- perversely strays,
Swerves from his God, and walks in devious ways.
-- Freebetter's "New England Almanack" for 1788

The June Solstice - - The Sun at 23 1/2 degrees North

Back in my public school days, I was taught that the Earth's axis is inclined "23 1/2 degrees" to the plane of its orbit around the Sun. Like many of the things I learned in public school this was an interesting factoid, but didn't help me very much in inderstanding what was going on in the sky. but this number "23 1/2 degrees" turns up in mnay intersting ways, especially around the solstices.

On June 21, the Earth reaches a point in its orbit where the North Pole is leaning in the general directgion of the Sun. As seen from the Earth's surface, the Sun appears to reach the northern extreme of its annual circle through the sky. So on this day, the Sun appears to "stand still" and not move further North. For this reason, the Romans called it the "solstice," which means in Latin, "The Sun stands."

On the June solstice, the Sun reaches its furthest extent to the North in the sky. For folks in the northern hemisphere, the Sun is highest overhead at Noon, and the Noon shadows are the shortest of the year. Also, the morning Sun is seen to rise furthest to North than any day of the year, and also sets furthest to the North. For this reason, the June solstice is "The Longest Day of the Year," and "The First Day of Summer" for everyone in the Northern Hemisphere.

-- from Classical Astronomy, 20 Jun 2012 issue, published by Jay Ryan, http://www.classicalastronomy.com

1 comment:

M and W said...

Oh good summer is finally here!!! I thought the shadows looked funny today.