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Old 27-02-2010, 11:24 AM
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ngcles
The Observologist

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Join Date: Dec 2006
Location: Billimari, NSW Central West
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Time Zones !!

Hi bethmercado2112,

Quote:
Originally Posted by bethmercado2112 View Post
Hi there, This "no full moon in Australia" still confuses me. I would appreciate if you enlighten me on this.

According to Geoscience Australia (http://www.ga.gov.au/geodesy/astro/m.../phase2010.jsp), the full moon in Australia is on FEB. 28. 2010 at 16 h 35 m.

The only month in recorded history that did not have full moon was on FEB 1865.

E. Mercado

bethmercado2112@yahoo.com
When you look at the table on that web-site you will see the times are in UTC (Universal Coordinated Time) -- that is for all intents and purposes Greenwich Mean Time.

At this time of year in Australia with daylight savings in operation (in some places) the states of the Australian mainland are between 8 and 11 hours ahead of UTC so Feb 28th 16:28 UTC when you add between 8 and 11 hours always brings you into the early hours of 1st of March. For all time zones between +8 and +11 UTC, there will be no Full Moon in February.

These time zones bascially include all New Zealand, Australia, and most of east Asia (Japan, China, Korea, Indo-China, Malaysia, Indonesia & India) -- including about 1/2 the world's population BTW. But, does not include Central Asia, Europe, Africa, North or South America. In the USA, because you good folks are (from memory) about 6 to 8 hrs behind UTC don't get a full-Moonless Feb -- this time.

The Full-Moonless month thing can only happen in February because it is the only month shorter than the Moon's average Synodic Period. The Synodic period is the period between *exact* phases of the Moon (eg Full Moon to Full Moon) in successive months (lunations). It is on average 29.5 (odd) days.

See Synodic Month: http://en.wikipedia.org/wiki/Synodic...#Synodic_month

(Short Extrract)

Synodic month
This is the average period of the Moon's revolution with respect to the sun. The synodic month is responsible for the moon's phases, because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth. While the moon is orbiting the earth, the Earth is progressing in its orbit around the Sun. This means that after completing a sidereal month the Moon must move a little farther to reach the new position of the Earth with respect to the Sun. This longer period is called the synodic month (Greek: σὺν ὁδῴ, sun hodō, meaning "with the way [of the sun]"). Because of perturbations in the orbits of the Earth and Moon, the actual time between lunations may range from about 29.27 to about 29.83 days. The long-term average duration is 29.530589 days (29 d 12 h 44 min 2.9 s). The synodic month is used in the Metonic cycle.

The Moon's orbital cycle repeats approximately every 19 years and is known as the Metonic Cycle.

http://en.wikipedia.org/wiki/Metonic_cycle

The Full-Moonless February thing is as a result of the resonance between the Synodic Period, the length of February (28 or 29 days) and the Metonic Cycle and so repeats on average every 19 years-odd (your milage may vary according to time zone!)

Hope this helps Beth.


Best,

Les D
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