Three Supermoons in a Row
 
July 10, 2014: In June of last year, a full Moon made headlines.  The news
media called it a "supermoon" because it was 14% bigger and 30%
brighter than other full Moons of 2013.   Around the world, people went
outside to marvel at its luminosity.
 
If you thought one supermoon was bright, how about three..? The full Moons
of summer 2014-July 12th, August 10th, and Sept. 9th--will all be
supermoons.
 
http://youtu.be/D1KKpeW231Y
 
A new ScienceCast video counts the supermoons of summer 2014. Play it
 
The scientific term for the phenomenon is "perigee moon." Full
Moons vary in size because of the oval shape of the Moon's orbit. The Moon
follows an elliptical path around Earth with one side ("perigee")
about 50,000 km closer than the other ("apogee").  Full Moons
that occur on the perigee side of the Moon's orbit seem extra big and
bright.
 
This coincidence happens three times in 2014.  On July 12th and Sept 9th
the Moon becomes full on the same day as perigee.  On August 10th it
becomes full during the same hour as perigee-arguably making it an
extra-super Moon."
 
It might seem that such a sequence must be rare. Not so, says Geoff Chester
of the US Naval Observatory.
 
"Generally speaking, full Moons occur near perigee every 13 months and
18 days, so it's not all that unusual," he says. "In fact, just
last year there were three perigee Moons in a row, but only one was widely
reported."
 
In practice, it's not always easy to tell the difference between a
supermoon and an ordinary full Moon. A 30% difference in brightness can
easily be masked by clouds and haze.  Also, there are no rulers floating in
the sky to measure lunar diameters. Hanging high overhead with no reference
points to provide a sense of scale, one full Moon looks about the same size
as any other.
 
Chester expects most reports of giant Moons this summer to be ... illusory.
 
http://tinyurl.com/ojq9gaa
 
Perigee is the point in the Moon's elliptical orbit closest to Earth.
Diagrams:#1, #2 "The `Moon Illusion'  is probably what will make
people remember this coming set of Full Moons, more than the actual view of
the Moon itself," he says.
 
The illusion occurs when the Moon is near the horizon.  For reasons not
fully understood by astronomers or psychologists, low-hanging Moons look
unnaturally large when they beam through trees, buildings and other
foreground objects. When the Moon illusion amplifies a perigee Moon, the
swollen orb rising in the east at sunset can seem super indeed.
 
"I guarantee that some folks will think it's the biggest Moon they've
ever seen if they catch it rising over a distant horizon, because the media
will have told them to pay attention to this particular one," says
Chester.
 
"There's a part of me that wishes that this 'super-Moon' moniker would
just dry up and blow away, like the 'Blood-Moon' that accompanied the most
recent lunar eclipse, because it tends to promulgate a lot of
mis-information," admits Chester. "However, if it gets people out
and looking at the night sky and maybe hooks them into astronomy, then it's
a good thing."
 
Indeed it is.
 
Mark your calendar--July 12th, August 10th, and Sept. 9th -and enjoy the
super-moonlight.
 
Credits:
Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:
Science{at}NASA
 
 
Regards,
 
Roger

--- D'Bridge 3.99