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Астронет: Астрономическая картинка дня Лунное гало над каменным кругом http://variable-stars.ru/db/msg/1408558/eng |
Credit & Copyright: Alyn Wallace Photography
Explanation:
Have you ever seen a halo around the
Moon?
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 Moon Halo.
A similar Sun Halo
may be visible during the day.
Exactly
how ice-crystals form
in clouds remains under investigation.
In the featured
image, the ice
circle in the sky is mirrored by a stone circle on the ground.
Taken just over a month ago in
Pontypridd Common,
Wales,
UK, the central
Rocking Stone survives from the
last
ice age, while the surrounding
stones in the circles were placed much more recently -- during the 1800s.
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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.