First of the Supermoon Trilogy on Dec. 3, 2017
Dear Friends & Neighbors,
(Please click on red links & note magenta)
The first and only supermoon of 2017 appeared yesterday, Dec. 3, 2017, 16% brighter and 7% larger than normal, because the lunar orbit of the earth is not perfectly circular, therefore its distance to earth varies. A supermen occurs when the perigee (the closest point to the earth in the orbit of the moon) coincided with the full moon. This makes the moon look bigger and brighter in the sky than normal. Yesterday’s full moon was 222,761 miles from earth, closer than the average 238,900 miles. NASA described this event as the first of a “supermoon trilogy”, with two more on Jan. 1 and Jan 31 in 2018.
The Moon’s distance varies each month between approximately 357,000 and 406,000 kilometers (222,000 and 252,000 mi) because of its elliptical orbit around the Earth (distances given are centre-to-centre).
A full moon at perigee is visually larger up to 14% in diameter than at apogee. While the moon’s surface luminance remains the same, because of its larger size the illuminance is up to 30% brighter than one at its farthest point, or apogee. While a typical summer full moon at temperate latitudes provides only about 0.05-0.1 lux, a supermoon directly overhead in the tropics could provide up to 0.36 lux.
The name supermoon was coined by astrologer Richard Nolle in 1979, arbitrarily defined as:
… a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth.
Nolle also claimed that the moon causes “geophysical stress” during the time of a supermoon. Nolle never outlined why he chose 90%.
The term perigee-syzygy or perigee full/new moon is preferred in the scientific community. Perigee is the point at which the Moon is closest in its orbit to the Earth, and syzygy is when the Earth, the Moon and the Sun are aligned, which happens at every full or new moon. Hence, a supermoon can be regarded as a combination of the two, although they do not perfectly coincide each time.
Gathered, written, and posted by Windermere Sun-Susan Sun Nunamaker
More about the community at www.WindermereSun.com
~Let’s Help One Another~
Please also get into the habit of checking at these sites below for more on solar energy topics: