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Circle 'round the Moon (APOD 2009 February 13)
Posted: Fri Feb 13, 2009 4:45 pm
by neufer
http://antwrp.gsfc.nasa.gov/apod/ap090213.html
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. Hamlet : Act II, scene II
GUILDENSTERN: Prism, my lord!
HAMLET: Denmark's a prism.
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http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/halo22.html wrote:
<<The familiar 22° halo around the Sun or Moon occurs because of refraction in tiny hexagonal ice crystals in the air. With the 60° apex angle of the prism formed by extending the sides of the crystal and the index of refraction of ice (n=1.31) one can calculate the angle of minium deviation to be 21.84°. Further refinement using n=1.306 for red and n=1.317 for blue gives angles of 21.54° and 22.37° for red and blue respectively. The inner edge of the halo is sharp and appears reddened - the angle of minimum deviation for red is less and you see it from crystals closer to the Sun or Moon direction. The out edge of the halo is blue in appearance but less saturated because other wavelengths can refract at that angle.>>
http://antwrp.gsfc.nasa.gov/apod/ap080516.html
http://antwrp.gsfc.nasa.gov/apod/ap061109.html
http://antwrp.gsfc.nasa.gov/apod/ap060923.html
http://antwrp.gsfc.nasa.gov/apod/ap060613.html
http://antwrp.gsfc.nasa.gov/apod/ap050309.html
http://antwrp.gsfc.nasa.gov/apod/ap040804.html
http://antwrp.gsfc.nasa.gov/apod/ap020114.html
Re: Circle 'round the Moon (APOD 2009 February 13)
Posted: Sat Feb 14, 2009 8:12 pm
by DavidLeodis
The explanation states the image was taken last Sunday morning, which was February 8th. However, in the information with the image in Laurent Laveder's PixHeaven website (the image was brought up through the "sight of a bright lunar halo" link in the explanation) it states it was taken on January 8th 2009 (which was a Thursday). I find it interesting to know the date when APOD images were taken, so I am wondering if anyone could please confirm which date is correct.
Also, I'm curious about the use of " 'round " in the APOD title. Is 'round the US spelling of around?
Re: Circle 'round the Moon (APOD 2009 February 13)
Posted: Sat Feb 14, 2009 10:59 pm
by neufer
DavidLeodis wrote:The explanation states the image was taken last Sunday morning, which was February 8th. However, in the information with the image in Laurent Laveder's PixHeaven website (the image was brought up through the "sight of a bright lunar halo" link in the explanation) it states it was taken on January 8th 2009 (which was a Thursday). I find it interesting to know the date when APOD images were taken, so I am wondering if anyone could please confirm which date is correct.
PixHeaven has February 8th 2009:
http://www.pixheaven.net/geant/090208_8200-17.html
which better coincides with the Full Moon:
* January 11, 03:27 UT
* February 9, 14:49 UT
Re: Circle 'round the Moon (APOD 2009 February 13)
Posted: Sat Feb 14, 2009 11:09 pm
by DavidLeodis
Thanks neufer. It would seem that the January 8th 2009 date that Laurent gives in his website is wrong and should be February 8th.
Re: Circle 'round the Moon (APOD 2009 February 13)
Posted: Sun Feb 15, 2009 12:08 am
by apodman
DavidLeodis wrote:I'm curious about the use of " 'round " in the APOD title. Is 'round the US spelling of around?
Not so much a US spelling as a poetic option. It sometimes helps the pattern of accented and unaccented syllables for the tongue and the ear. "Ring around the moon" has the same meter as "circle 'round the moon". C'mon, children, gather 'round, form a ring around the fire. It is a break from formal writing in any case. Generally "'round" can be used when the preceding word ends in an unaccented syllable that the ear can accept as a substitute for the leading "a" in "around"; hence the use of "'round" after "circle" and "gather", but "around" after "ring".
Re: Circle 'round the Moon (APOD 2009 February 13)
Posted: Sun Feb 15, 2009 5:42 pm
by DavidLeodis
Thanks apodman. The use of 'round just looked a bit odd to me in the title. I'm clearly not poetic enough for the forum!