Astronomy Picture of the Day
Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
2010 February 8
A Sun Halo Over Cambodia Credit &
Copyright :
Nagy Attila
Explanation:
Have you ever seen a halo around the Sun?
This fairly common sight occurs when high thin clouds containing millions of tiny
ice crystals cover much of the sky.
Each
ice crystal acts like a
miniature lens .
Because
most
of the crystals have a similar elongated
hexagonal
shape, light entering one crystal face and exiting
through the opposing face refracts 22
degrees ,
which corresponds to the radius of the Sun halo .
A similar Moon halo
may be visible during the night.
Pictured above , a nearly complete
sun halo was photographed high above the ancient
Bayon temple in
Angkor ,
Cambodia .
Exactly how
ice-crystals form in clouds remains under
investigation .
Tomorrow's picture: night launch
<
| Archive
| Index
| Search
| Calendar
| RSS
| Education
| About APOD
| Discuss
| >
Authors & editors:
Robert Nemiroff
(MTU ) &
Jerry Bonnell (UMCP )NASA Official: Phillip Newman
Specific rights apply .NASA Web
Privacy Policy and Important Notices A service of:
ASD at
NASA /
GSFC
& Michigan Tech. U.
