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Credit & Copyright: Anthony Ayiomamitis
Explanation:
Astronomically speaking, at the Equinox on
March 21, 01:00 UT (March 20, 8:00 PM ET) the season changes.
For this Equinox the Sun rises
due east as it crosses the celestial equator heading north.
In celebration, consider this spectacular sunrise analemma!
An
analemma is the figure-8 loop you get when you mark the
position of the Sun at the same time each day throughout the year.
In
this remarkable case, 38 separate exposures
(and 1 foreground exposure) were recorded on a single piece of film
between January 12 and December 21, 2002 at 06:00 UT.
The tilt of planet Earth's axis and the variation
in speed as it moves around its
elliptical orbit combine to produce the
predictable analemma curve.
The top and bottom of the figure-8 correspond to the
Solstices -- the Northern
and Southern limits of the Sun's sky motion.
The two Equinoxes
find the
Sun at points along the
anelemma curve exactly half way between the Solstices.
Here, the analemma's Southern portion is partly hidden by
mountains.
In the foreground
lie the stone ruins of
the Tholos
at the ancient site of Delphi, Greece.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: analemma - equinox - solstice
Publications with words: analemma - equinox - solstice
See also: