RE: THOUGHT YOU MIGHT BE INTERESTED
chester.geoff@usno.navy.mil
Tue, 14 Dec 1999 14:10:49 -0500
I've been getting assaulted by this one for the past few days. Even more
than the usual "when is the real millennium" questions (answer is 2001, BTW
:-) )
The coincidence of Full Moon with the solstice is about every 19 years...the
ol'
Metonic Cycle. The coincidence of a Full Moon at lunar perigee (and the
closest
for the year at that) is about every 13.5 months. The coincidence of
closest
lunar perigee, Full Moon, and winter solstice is a bit more rare...on the
order
of once a Century.
However, claims of a brighter Moon are quite overblown. The difference
between
Full Moon at closest lunar perigee and earth perihelion versus Full Moon at
lunar apogee
and earth aphelion amounts to about 1/3 of a magnitude...-12.6 vs. -12.9.
The
Moon's so bright to begin with that most folks couldn't detect the
difference
unless they had a good pocket photometer.
The claim about headlights being superfluous is a bit of a stretch. The Sun
is
still nearly 200,000 times brighter than the Full Moon, so it'll still be
pretty
dark no matter how much snow cover there is!
Cheers,
Geoff
+===========================================================+
| Geoff Chester grc@usno.navy.mil Public Affairs Office |
| http://www.usno.navy.mil US Naval Observatory |
| (202) 762-1438 3450 Massachusetts Avenue, NW |
| (202) 762-1489 (FAX) Washington, DC 20392 |
|-----------------------------------------------------------|
| "Each passing hour brings the Solar System 43,000 miles |
| closer to the globular cluster M13 in Hercules; yet there |
| are still some misfits who insist there's no such thing |
| as progress!" -- Ransom K. Fern |
+===========================================================+
> -----Original Message-----
> From: Hedgepet@stihl.de [mailto:Hedgepet@stihl.de]
> Sent: Tuesday, December 14, 1999 13:19
> To: SeeSat-L@blackadder.lmsal.com
> Subject: FW: THOUGHT YOU MIGHT BE INTERESTED
>
>
> This is slightly off-topic, but it will affect our ability to observe.
> Plus, its interesting astronomical stuff.
>
> Merry Christmas,
>
> Troy
>
> PS -- I don't have any reference material or links for this.
> It is word of
> mouth to me.
>
> <snip>
>
> Brightest Full Moon in 133 years on the Winter Solstice
>
> For the first time in the life of anyone around today, we'll
> see a full
> moon occur on the Winter solstice, Dec. 22nd, commonly
> called the first day
> of Winter.
>
> Since a full moon on the Winter solstice occurs in conjunction with a
> lunar perigee (point in the moon's orbit that is closest to
> Earth),the moon
> will appear about 14% larger than it does at apogee (the
> point in its
> elliptical orbit that is farthest from the Earth). Since the
> Earth is also
> several million miles closer to the sun at this time of the
> year than in
> summer, sunlight striking the moon is about 7% stronger
> making it brighter.
> Also, this will be the closest perigee of the Moon of the
> year since the
> moon's orbit is constantly deforming. If the weather is
> clear and there is
> snow cover where you live, it is believed that even car
> headlights will be
> superfluous. On December 21st, 1866 the Lakota Sioux took
> advantage of this
> combination of occurrences and staged a devastating
> retaliatory ambush on
> soldiers in Wyoming Territory. In layman's terms: It will be
> a super bright
> full moon, much more than the usual AND it hasn't happened
> this way for 133
> years! Our ancestors 133 years ago saw this. Our descendants
> 100 or so
> years from now will see this again.
>
> Pretty cool, eh?
> <snip>
>
>
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