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Астронет: Астрономическая картинка дня Ложные луны над Аляской http://www.variable-stars.ru/db/msg/1278372/eng |
Credit & Copyright: Sebastian
Saarloos
Explanation:
Moonlight illuminates a snowy scene in
this
night land and skyscape made on January 17 from
Lower Miller Creek, Alaska, USA.
Overexposed near the mountainous western horizon is
the first quarter Moon itself, surrounded by an
icy halo and flanked left and right
by moondogs.
Sometimes called mock moons, a more scientific name for
the luminous apparations
is paraselenae (plural).
Analogous to a sundog or parhelion,
a paraselene is produced by moonlight refracted through thin,
hexagonal, plate-shaped ice crystals in high
cirrus clouds.
As determined by
the
crystal geometry, paraselenae are seen
at an angle of 22 degrees or more from the Moon.
Compared to the bright lunar disk,
paraselenae are faint
and easier to spot when the Moon is low.
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.