The Full Moon of Wednesday, Sept. 10 also carries the title of the Harvest Moon for those living in the Northern Hemisphere. This year it arrives earlier than is typical.
The annual Harvest Moon is defined as the Full Moon that arrives nearest to the fall equinox, which is on Sept. 23. In one out of three years the Harvest Moon is in October. The 2003 version comes unusually early, although it can occur as early as Sept. 8 (as in 1976) or as late as October 7 (as in 1987).
The Moon officially turns full when it reaches a spot in the sky opposite to the Sun in our sky. This moment will occur at 16:36 Greenwich Time (12:36 p.m. EDT or 9:36 a.m. PDT) on Wednesday.
Many people think that the Harvest Moon remains in the night sky longer than any of the other Full Moons we see during the year, but that is not so. What sets it apart is that farmers at the climax of the current harvest season can work late into the night by the Moons light. able -->
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The Moon at 9 p.m. on Sept. 10 as seen from mid-northern latitudes. The green line is the ecliptic, along with the Sun, Moon and planets roughly track.
* Graphic made with Starry Night Software
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A Full Moon always rises about the time the Sun sets. But at this time of year, instead of rising its normal average 50 minutes later each day, the Moon seems to rise at nearly the same time each night. Below weve provided some examples for ten North American cities.
The local moonrise times for Sept. 9, 10 and 11 are provided, the middle date being that of the Harvest Full Moon. The Moon will appear nearly fully on each of these nights.
In actuality, over this three-night interval for our relatively small sampling, the rising of the Moon comes, on average, just over 23 minutes later each night. A quick study of the table shows that the night-to-night difference is greatest for the more southerly locations (Miami, located at near latitude 26N, sees moonrise come an average of just under 33 minutes later). Meanwhile, the difference is less at more northerly locations (at Edmonton, Alberta, located at latitude 53.6N, the average difference is less than 12 minutes).
Why the strange seasonal circumstance? The Moon appears to move along the ecliptic, an arc in the sky that the Sun also traces out. At this time of year when rising, the ecliptic makes its smallest angle with respect to the horizon for those living in the Northern Hemisphere.
In contrast, for those living in the Southern Hemisphere, the ecliptic at this time of year appears to stand almost perpendicular (at nearly a right angle) to the eastern horizon, so the difference for the time of moonrise exceeds the average of 50 minutes per night. At Melbourne, Australia, for instance, the night-to-night difference amounts to 64 minutes.
Interestingly, for those who live near 60 North latitude, the Moon does indeed appear to rise at the same time each night around the time of the Harvest Moon.
And for those who live even farther to the north, a paradox: the Moon appears to rise earlier! At Reykjavik, Iceland (latitude 64.2N), the times of moonrise on Sept. 9, 10 and 11 will be, respectively, 8:55 p.m., 8:49 p.m. and 8:43 p.m.
Moonrise Times
For select locations during the Harvest Moon of 2003.
Location Sept. 9 Sept. 10 Sept. 11
Albuquerque, NM
7:19 p.m. MDT
7:47 p.m. MDT
8:13 p.m. MDT
Chicago, IL
7:12 p.m. CDT
7:35 p.m. CDT
7:57 p.m. CDT
Denver, CO
7:19 p.m. MDT
7:44 p.m. MDT
8:07 p.m. MDT
Edmonton, AB
8:21 p.m. MDT
8:33 p.m. MDT
8:44 p.m. MDT
Houston, TX
7:26 p.m. CDT
7:57 p.m. CDT
8:26 p.m. CDT
Los Angeles, CA
7:05 p.m. PDT
7:33 p.m. PDT
8:00 p.m. PDT
Miami, FL
7:19 p.m. EDT
7:52 p.m. EDT
8:24 p.m. EDT
Montreal, QC
7:22 p.m. EDT
7:43 p.m. EDT
8:01 p.m. EDT
New York, NY
7:15 p.m. EDT
7:39 p.m. EDT
8:01 p.m. EDT
Seattle, WA
7:43 p.m. PDT
8:02 p.m. PDT
8:19 p.m. PDT
2007-08-13 07:11:16
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