Jimmy Westlake: ‘Super moon’ or super hype?
May 7, 2012
I can't help but chuckle a little when the news media pick up on a rather mundane celestial event and blow it way out of proportion. Such was the case with this past weekend's so-called "super moon." I heard one TV talking head announce that the moon would look 60 percent larger than normal in our sky. Let me see if I can help set the record straight.
Of course, we have a full moon once every month, so nothing is unusual about that. Occasionally, two full moons will fall into one calendar month, and this non-event is dubbed by some as a "blue moon." Unusual? Yes, but nothing to get all that excited about. And because of the moon's non-circular orbit around the Earth, it swings in to its perigee, or closest point to Earth, once per month, then swings out to its apogee, or farthest point from Earth, also every month. Happens every month, so nothing unusual about that, either.
But for some reason, when these two monthly non-events coincide to create a perigee full moon, it makes headline news for several days in a row. Common anecdotes about the full moon include a higher crime rate, higher birth rate and higher tides. The only one of these three that has any evidence to back it up is the part about higher tides. Twice each month, at new moon and full moon, the moon and sun tug on the Earth along the same straight line and produce what are called spring tides. The name comes from the German verb "springen," which means to rise up. Folks living along coastal areas might notice an extra inch or 2 of water twice per month in this spring tide, but again, nothing to get all that excited about.
According to NASA, when the moon is at its closest point to Earth, it is about 14 percent closer than when at its farthest point. The average person would be hard pressed to look up in the big, open sky and discern that tiny difference. If the moon happens to be full at the same time that it reaches its perigee point, as it was this past weekend, it can appear as much as 30 percent brighter than an apogee full moon. Without having the two side-by-side for an easy comparison, it's doubtful that the average moon-watcher can tell the difference.
So, I watched the super moon with interest Saturday night, pulled out the telescope and snapped a few pictures, then went on to bed with the bright moonlight streaming in the window. When my wife and I received an excited call from our son in Georgia on Sunday morning telling us that his wife had gone into labor with our third granddaughter, we thought, "Wow! Maybe there is something to this super moon stuff." Turned out to be false labor pains, so we are still waiting for the newest arrival to our family. I guess that lovely super moon was just super hype after all.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Visit his website at http://www.jwestlake.com.