Supermoon

Last night, we had the first of three so-called supermoons this summer. It is the phenomenon where the moon appears to subtend a larger angle in the sky due to it’s close proximity to the Earth. We’re due to have another, even larger supermoon on August 10th.

From Wikipedia

A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth-Moon-Sun system. The term “supermoon” is not astronomical, but originated in modern astrology. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but the evidence of such a link is widely held to be unconvincing.

The most recent occurrence was on July 12, 2014. The next and closest supermoon of 2014 will be on August 10.

The opposite phenomenon, an apogee-syzygy, has been called a micromoon, though this term is not as widespread as supermoon.

Although the reference to supermoons causing earthquakes is “held to be unconvincing,” I still remember the 1971 Sylmar quake which occurred the morning after a supermoon. I remain completely unconvinced that anything other than terrestrial tectonic plate movement had anything to do with that event.