A “super moon” occurs when the moon is full (or new) and is also at it’s closest approach to the Earth (perigee). When this happens, the full moon appears bigger and brighter compared to other full moons. The difference in size is only 16% compared to the smallest full moon – a full moon at apogee or micro moon. So it’s actually very hard to notice the larger apparent size unless you see the super moon presented beside the micro moon.
While i don’t like the term “Super Moon” the media has latched onto it, so that’s what i’ve call this post. The correct term according to wikipedia is “perigee-syzygy of the Earth-Moon-Sun”. Ok, doesn’t roll off the tongue very well. But a simpler term is “perigee moon”. Perigee meaning the point where the moon is closest to earth during it’s monthly orbit. Both a full moon and new moon at perigee are considered a “super moon”, but the media doesn’t seem to care about the new moon event. (At new moon you can’t actually see the moon since it’s directly in line with the sun.)
When a full moon or new moon occurs, the sun, earth and moon are aligned so their mutual gravitational forces are also aligned and the combined affect on the earth’s oceans is at it’s greatest. At perigee the moon’s gravitational pull on the earth is also at a maximum. So the combined affect of the sun and the super moon can have a mild affect on tides. And if a perigee moon occurs in spring when tides are already at their highest, the additional affects of a perigee moon can be noticeable.
It’s always reported in the media that the perigee full moon makes the tides higher. But it occurs to me that at full moon, the moon and sun are on opposite sides of the earth. So it would seem their gravitational pull on the oceans should cancel out and the tides would therefore be smaller. I don’t know if this is the case however.
Usually there are 2, and occasionally just one perigee moon in a calendar year. The coincidence of full moon with perigee occurs every 13.94 months. The new moons before and after the full moon can also be at perigee so it’s possible to have 3 super moons in one calendar year. This occurred in 2014 with super moons on July 12th, August 10th, and Sept. 9th.
On September 8th, i took a photograph of the almost full moon just around sunset – or moon rise.
The next day was actually the super moon event and i took this photo: