Kern arc

The Kern arc is a rare sky phenomena.
alt=Kern arc|thumb|Kern arc
This phenomenon is so rare that it has been reported six times. It has been photographed only once by Finnish astrophotographer Marko Mikkilä.

 Name 
The Kern arc got its name from the Dutch scientist H.F.A. Kern, who was the first to see and report it on 8 October, 1895.  

 Appearance 
It looks like a white ring around the zenith, the point straight up from you. It belongs to the family of ice crystal halos, and although it looks different than the more common circumzenithal arc which is only half of an arc, they often appear at the same time. 

 Cause 
The Kern arc is created by the scattering of sunlight through specific ice crystal shapes, specifically triangles. 

 References 

Category:Atmospheric optical phenomena