Planet Save – by Sandy Dechert
Look up this weekend, just as we advised you to for the blood moon and total lunar eclipse in April! A “Supermoon,” one of the largest moons of the year, will come visiting. Both Friday and Saturday nights should provide good viewing, though the phenomenon actually occurs at 7:25 am EDT Saturday.
This July moon is also known as a Full Buck Moon, because it appears at the time male deer (bucks) begin to sprout antlers; or as a Thunder Moon. Those familiar with July in the States can figure out where Thunder Moon gets its name.
A supermoon makes the Moon’s disk look exceptionally large when seen by humans from Earth. At perigee, our natural satellite can appear up to 14% larger and 30% brighter than when it is at apogee, its farthest point. Low-hanging moons near the horizon appear biggest.
Although it seems esoteric, the supermoon actually occurs pretty regularly. AstrologerRichard Nolle coined the term “supermoon” in 1979, defining it 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.”
OK for an astral fortuneteller, but sky science specialists really think of a supermoon as occurring when a full moon or new moon (syzygy) actually coincides with perigee—the closest time the Moon, on its elliptical orbit, ever gets to the Earth. Perigee distances vary from 221,450 to 230,150 miles (356,400 to 370,400 kilometers, center-to-center). However, most astronomers will let you get away with the looser definition of supermoon as the proxigean moon, occurring within 24 hours of perigee.
The last encounter this close between the Earth and the Moon was just over a year ago, on June 23, 2013. We’re having five rogue moon events this year. Two lesser ones took place in January. Then we have this weekend’s July supermoon—but even it won’t be the biggest of 2014. The year’s recordbreaker will occur next month, on August 10 at 2:11 pm EDT. Here’s NASA’s story (VIDEO).
And if it rains in your neck of the woods on both nights, do not despair! The Harvest supermoon will be along in September.
http://planetsave.com/2014/07/11/three-summer-supermoons-2014-start-saturday-video/