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Астронет: Астрономическая картинка дня "Солнечный кинжал" на скале http://variable-stars.ru/db/msg/1683951/eng |
Credit & Copyright: Martha Schaefer,
Brad Schaefer,
Jim Stamm;
Music & License:
Awakening
(Wojciech Usarewicz),
Lone Tree Music
Explanation:
Ancient sun daggers will not hurt you, but they may tell you the time.б
A sun dagger is a dagger-shaped gap in a shadow created by sunlight
streaming throughбa crevice in a nearby rock.
Starting over a thousand year ago, native
people of the American southwest carved spiral
petroglyphs
into rocks that became illuminated by
sun daggers
in different ways as the
Sun
shifts in the sky.
A type of sundial, where the
end of the
sundagger points in
the spiral at high noon (for example) indicates a time of year, possibly illuminating
a
solstice or
equinox.б
Sun daggers
are thought to have been used by
Sun Priests
during lone vigils with prayers and offerings.б
Of the few known, the
featured video
discusses the historic
Picture Rocks Sun Dagger
near Tucson,
Arizona,
USA,
likely created by a
Hohokam Sun Priest around 1000
AD.б
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.