Астронет: Астрономическая картинка дня Когда Луна становится "голубой" http://variable-stars.ru/db/msg/1198829/eng |
Credit & Copyright: Vic Winter (ICSTARS)
Explanation:
How often does a full moon occur twice in a single month?
Exactly once in a
Blue Moon.
In fact, the modern usage of the term "Blue Moon" refers to the
second Full Moon in a single month.
Tonight's Blue Moon will be the first since November 2001.
A Blue Moon typically
occurs every few years.
The reason for the rarity of the
Blue Moon is that the 29.53 days between full moons is
just slightly shorter than the number of days in the average month.
Don't, however, expect the moon to look blue tonight!
The term "Blue Moon" has recently been traced to an error in a
magazine article in 1946.
It is possible for the
Moon to appear tinged by a blue hue, sometimes caused
by fine dirt circulating in the
Earth's atmosphere, possibly from a volcanic explosion.
The above picture was taken not during a full moon but through a morning sky that
appeared dark blue.
The bright crescent is the only part directly exposed to sunlight - the rest of the
Moon glows from sunlight reflected from the Earth.
In this dramatic photo, however, the planet
Jupiter
is also visible along with its
four largest moons.
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.