Image Credit & Copyright: Rick Baldridge (links below).
The fifth and final supermoon of 2014 is scheduled to occur on the Harvest moon; Monday September 8th at 21:39 EDT (01:39 UTC on the 9th) where it will be at a distance of 358,387 km (222,691 mi).
Before we go too far lets touch on a couple valuable lunar definitions.
PERIGEE: The moons closest point from Earth in its 29.5 day synodic cycle.
APOGEE: The moons furthest point from Earth in its 29.5 day synodic cycle.
SUPERMOON: A new or full moon within 90% of perigee. These moons are officially designated as proxigean or the more modern perigee moons.
On average, supermoons are approximately 14% larger and 30% brighter than an apogee full moon. That sure does sound like a lot (and it is) but it’s really difficult to notice the difference. Even those of us who view the moon all month long for its different features have a hard time distinguishing the difference in apparent size. As far as what they do…..well, not much really. You may notice larger than normal tides but even then were not talking about much. If you live in a low lying costal area you may notice a difference of a few feet, maximum.
As far as brightness, again the difference will be tough to tell unless you frequently wander outside at night during full moons, which, I always recommend by the way. Even in the smallest of low lying summer full moons, once your eyes are dark adapted there is so much light that you can easily navigate on foot and even see color. In the winter months when the moon reaches high into the night sky it’s very bright. So supermoon’s may be bright but your average winter full moon will likely out shine it.
Historically (and still today) astronomers call a full or new moon that lands on the night of perigee a perigee or proxigean full or new moon, though due to the title supermoon catching on many are running with the name supermoon as it’s a pretty cool name and the parameters that it works within allow for about 4-6 per year. The term supermoon comes not from science but from astrology; more specifically, astrologer Richard Nolle who coined the phrase and set guidelines that state any NEW or FULL Moon within 90% of perigee is a supermoon. So there you go, and it’s not a big deal but either way it’s encouraging people who otherwise wouldn’t be looking up to do so and that is certainly a good thing in my opinion. If you have questions, as always please ask.
It’s worth noting that August’s supermoon was the biggest and closest of 2014 at a distance of 356,896 km (221,765 mi.) but in the following few years it will get even closer and larger; September 28, 2015 at a distance of 356,877 km (221,753 mi.) / November 14, 2016 at a distance of 356,509 km (221,524 mi.).
In 2015 there will be six supermoons (three new moons & three full moons) with September’s being very special as it occurs at an intersection of a few major lunar events happening at the same time. Let’s have a look.
2015 SUPERMOONS: (Six)
January 20: (New Moon)
February 18: (New Moon/Seasonal Black Moon)
March 20: (New Moon)
August 29: (Full Moon)
September 28: (Full Moon, Closest Supermoon of the Year, Harvest Moon & Total Lunar Eclipse which also completes a Tetrad!)
October 27: (Full Moon)
Rick Baldridge Flickr: https://www.flickr.com/photos/xb70man/
University of California Observatories: http://www.ucolick.org/