Get ready for quite a show with this month’s full moon. The November full moon is always known as the Beaver Moon but this year we get to call it a supermoon as well. It very well may be a once in a lifetime viewing event and it will occur exactly at 8:42 AM EST on November 14th.
Apogee and Perigee
The moon’s orbit around Earth is far from a perfect circle. The 27 day voyage of Earth’s satellite is actually an elliptical orbit with an ever changing distance. The casual observer will notice the phases of the moon as it makes this orbit but the more subtle change, and also noticeable, is the slight change in distance as well. During the course of any given month the distance between the Earth and the moon will vary by close to 30,000 miles. The farthest point is called apogee, the moon being a distant 252,712 miles from Earth. Perigee is the closest point with that distance shrinking to 221,519 miles. A full moon at perigee will appear 14 percent larger and 30 percent brighter than a full moon at apogee.
This Month’s Supermoon
The November 14th full moon will occur within 2 hours of the point when the moon is at perigee. This is something that has not happened since January of 1948 and will not happen again until November of 2034. This will put the November full moon in the supermoon class, a term that was coined by astrologer Richard Nolle in 1979. Nolle used the supermoon term to describe a new or full moon that occurs when the moon is in the top 10% of it’s closest distance to Earth. There was never a reason given why the 10% value was chosen and the term “supermoon” is not recognized in the astronomical community, but has certainly taken hold with the general population and media reports. Given that every 27 days there is a full and new moon along with perigee and apogee point the supermoon is not that uncommon, but the fact that the full moon and perigee will occur just 2 hours apart makes this month’s supermoon a rare sight.
What does it mean?
A great viewing opportunity is a given provided a clear sky. There will also be some unwanted effects of the full moon/perigee combination. The ebb and flow of the tides is a direct result of the moon’s gravitational pull on the Earth’s waters. During a new and full moon this force is not competing with the Sun’s smaller gravitational pull and can lead to higher than normal tides. These spring tides occur typically twice a month and are never really noticed by anyone. This gravitational force however can change and is directly related to the distance between two objects, shorten that distance and that force will increase. So when you have a regular spring tide along with a supermoon then you may be in for minor flooding on or near each high tide.
Look towards the east just as the sun is setting November 13, 14 and 15. The best time to really appreciate the supermoon will be as the moon is close the the horizon and will appear larger due to the moon illusion phenomenon. The beaver moon, called this because this was typically the time to set the beaver traps before the waters froze, will not look this big and bright for another 18 years.
See how one photographer captures the moon in stunning pictures around New York City here: Photographer Wows with NYC Imagery