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Астронет: Астрономическая картинка дня Аналемма-2010 http://variable-stars.ru/db/msg/1248946/eng |
Credit & Copyright: Tamas Ladanyi
(TWAN)
Explanation:
Looking
back on the year, have you wondered
where the Sun was in the sky each day during 2010 at exacty 9am
UT?
Of course you have. Search no further for the answer!
It was somewhere along this celestial figure 8 curve known
as an analemma.
Recorded from a residential backyard in the small town of
Veszprem, Hungary,
this
composite analemma image consists of
36 separate exposures of the Sun made at 9:00 UT, spaced
throughout the year, plus a background image made without a solar filter.
The background image was taken on the sunny afternoon
of October 9 (13:45 UT).
On the left is the photographer's shadow.
The positions of the Sun at the 2010
solstice dates
are at the upper (June 21) and lower (December 21) extremes of
the
analemma curve.
On the equinox dates (March 20, September 23) the Sun was
along the curve
half way between the solstices.
The tilt of planet Earth's axis and the variation in speed as it moves
around its elliptical orbit combine to produce the graceful
analemma curve.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.