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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.á  
  
A sun dagger is a dagger-shaped gap in a shadow created by sunlight   
streaming througháa 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.á  
  
Sun daggers   
are thought to have been used by   
Sun Priests   
during lone vigils with prayers and offerings.á  
  
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.á  
  
  
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A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
  