Fun_People Archive
20 Dec
Big moon myth sweeps Internet.

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From: Peter Langston <psl>
Date: Mon, 20 Dec 99 14:49:34 -0800
To: Fun_People
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Subject: Big moon myth sweeps Internet.

X-Lib-of-Cong-ISSN: 1098-7649  -=[ Fun_People ]=-
[A little more on this one...  -psl]

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  By Alan M. MacRobert, Globe Correspondent, 12/20/1999

An astronomical urban legend racing around the country by e-mail chain
letter says that a special full moon will supposedly illuminate the Earth
on Wednesday night with a spectacular flood of brilliance.  Headlined:
"Next full moon brightest you'll ever see!" the notice says that due to a
rare confluence of events - a full moon occurring on the winter solstice
just as it appears at close orbital points to the Earth and Sun - the moon
will be bigger and brighter than it's been in more than 100 years. So
bright, in fact, that we may not need headlights on if we're driving at
night.  Even the Wall Street Journal got taken in with the hype and ran a
page one story about the "phenomenon" last week under the subhead:  "Big,
Bright and Close to Earth. It Could Well Play Tricks Not Seen in Many a
Moon." Well, before you make plans to bathe in the moonglow, here are the
facts. Wednesday's full moon will look normal. You won't see anything
unusual about it unless you psych yourself up pretty hard. But like all the
best e-mail legends, this one has kernels of truth that keep it alive and
multiplying out of control.  It is true, as the chain letter says, that the
moon will be at the perigee of its orbit: at its closest to the Earth for
this month.  It is true that this perigee will be a trace closer than any
of the moon's other monthly perigees this year.  And it is true that around
this time of year, both the Earth and moon are three percent closer to the
Sun than when the Earth is on the opposite side of its orbit in June and
July.  So Wednesday's moon will indeed appear a bit bigger and brighter than
usual. But only a bit. Add up all the effects, and this full moon turns out
to be about 19 percent brighter than average.  That's a smaller brightness
boost than it sounds. The difference would be just detectable to the human
eye if you could put an average full moon next to Wednesday's in the sky
and compare the two. Failing that, you'd need measuring instruments. A good
photographer's light meter, carefully calibrated against an average full
moon, would do the trick.  But a moon to dazzle the world? Fugeddabout it.
Of course, many people will go out Wednesday night and be amazed at the
moon's brightness. That's because the full moon is always bright. This will
likely be the first time some people pay attention.  Another part of the
letter that claims this is all happening because this full moon coincides
with the December solstice.  Solstices don't make the moon brighter or
fainter (though at this time of year the full moon does stand high in the
sky around the middle of the night, whereas a spring or summer full moon
rides lower across the sky).  The chain letter says this is the first time
the moon has been so near and bright in 133 years; "the Lakota Sioux took
advantage of the super bright full moon and staged a devastating retaliatory
ambush on soldiers in the Wyoming Territory," some letters state. The ambush
actually happened at high noon.  In fact, Roger W. Sinnott of Sky &
Telescope magazine finds that the moon was actually brighter (by a hair) on
January 15, 1930, January 4, 1912, and other dates.  The real news here is
the power of the Internet to spread a piece of random confusion. The
bright-moon story originated from the 1999 Old Farmer's Almanac, where it
lay dormant all year. Then someone paraphrased it into an e-mail (complete
with the Indian attack), added some exaggerations, and away it flew. Two
weeks ago no one seems to have heard of it. Within a few days it was
everywhere, and media outlets around the nation were calling the magazine
to ask about it.  An e-mail chain letter is a kind of computer virus, one
spread by people rather than machines. Harmless ones like this serve a
valuable function. They train people not to believe them (since no one likes
being made a fool twice). The moon myth hurt no one and should die a quick,
natural death three days from now. Maybe it will help immunize people
against more virulent strains.

Alan M. MacRobert is an associate editor of Sky & Telescope magazine in
Cambridge (

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