What is the significance of the "Summer Solstice? Why do our days get longer until June 21, then they get shorter?
The June or "Summer" Solstice occurs this year (2005) at Eastern Daylight Saving Time on Tuesday June 21st.
The June Solstice occurs as the constant 23.5 degree tilt of the Earth's axis brings the North Pole finally
to its fullest excursion down into the Earth's sunlit side at this time of year. At the same time the
South Pole has been carried to its fullest excursion into the Earth's nighttime side. These effects
actually -define- the geographic demarcations on the globe known as the
Arctic Circleand the Antarctic Circle.
For the last six months, here in the Northern Hemisphere, we have been experiencing longer and longer
daylight periods as the Sun rises further north and arcs incrementally higher across our skies and sets
further north each day. Today this process slows to a stop and will begin to reverse, retreating finally
to its minimum at the December Solstice at , December 21st (2005).
- ERIC CANALI
ALSO SEE: Attached diagram (c) 2005 E.G.Canali
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Editorís Note: This Science question was answered by a very experienced amateur astronomer,
who also works as a part-time Tour Guide at the Allegheny Observatory in
Allegheny Observatory provides public tours two nights a week from April through October;
pre-registration is necessary (by telephoning 412-321-2400), but the tours are free-of-charge.
For many years, Eric G. Canali was Floor Manager for the original Buhl Planetarium
and Institute of Popular Science in
. He also was a long-time member of the Pittsburgh
Amateur Astronomers' Association of Pittsburgh and is Founder of the South Hills
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