Saturday's Super Moon

The Super (Duper) Moon!

Saturday night we will have a full moon on the same night that the moon is at its nearest point in its orbit to Earth -- known as perigee.

This event has been recently labelled the "Super Moon." I only started hearing that term in the last couple of years. So just how "super" is this Super Moon?

First, the coincidence of the full moon and perigee occurs about once every 14 months, so to say that this is an unusual occurrence is a bit of a stretch.

The Super Moon, however, will be 25 percent brighter than the full moon at apogee (farthest from the Earth) and that just might be noticeable.

Now let's deal with a couple myths. There is a widespread rumor that natural disasters, earthquakes in particular, are more common near a Super Moon.

These rumors became more widely known after last year's Japanese earthquake and a tsunami (March 11) occurred in the same month as the Super Moon (March 19).

But notice that even in that case, the two events were separated by over a week -- the moon was not at all close to perigee or full when the earthquake occurred.  A more serious study of major earthquake and Super Moon dates shows no correlation between these events.

A much more common observation is that when a full moon is seen rising above the horizon (which must always occur at sunset), it looks enormous compared to when it is seen overhead.

And so Saturday's rising Super Moon should look colossal. This is a real effect; however, the actual apparent size of the rising moon is identical to the apparent size when the moon is overhead.

What we experience is an optical illusion. You can test this one yourself. Next time you see a full moon rising, hold up your thumb at arm's length and put it over the moon, looking at it with one eye. Your thumb should just cover the moon.

Then, when you look at the moon later that evening when it is farther up in the sky (and appearing to be smaller), try the same experiment. Again, your thumb will just cover the moon. Unless your thumb has shrunk that evening, you've proven that the massive rising full moon is just an illusion.

Lastly, I personally learned something very interesting that I had never known about Super Moons while writing this article and reading through a site listing perigee and apogee distances to the Moon.

When we have a Super Moon, this means that the orbit of the Moon is aligned to "point" at the Sun -- the Moon's orbit is elliptical (which is why the distance to the moon varies), and the long axis of the ellipse is pointed toward the sun on the date of the Super Moon.

The sun's gravity pulling on the moon during its orbit around the Earth then forces the orbit to become more elliptical than usual when this alignment occurs -- which means that the perigee distance is less than usual, and the apogee distance is greater than usual at these times.

So the Super Moon is even closer to us than it would be at its normal perigee.  The difference I would have thought to be small, but it turns out to be 8,000 miles (out of an average distance of 230,000 miles, another 3.5 percent).

Editor's note about the author: Aaron Turner is an amateur astronomer and aerospace engineer from Southbury.

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.

Jaimie Cura (Editor) May 03, 2012 at 03:04 PM
Aaron, welcome to Patch and thanks for writing this! Love this first blog and can't wait to read more!
G. Gerard May 03, 2012 at 11:14 PM
Very cool! Thanks
Nicole Ball May 04, 2012 at 01:59 PM
Does a super moon affect tides? I remember during Irene people were saying the Super Moon and a super high tide is what caused a storm surge along the shoreline... Would be interesting to find out! Thanks Aaron! And welcome to Patch!
Jeff Dupuis May 04, 2012 at 09:07 PM
@Aaron Turner: Excellent post, I always love explaining the Moon Illusion to people. I also like how you didn't select any of the common explanations for why we see this illusion, in fact you didn't select any explanation which is excellent because the actual cause is not known to science. There are some great theories, but the most common is that "its a comparative view against foreground objects like trees and buildings that makes the brain think the moon is closer, hence bigger." This is easily proven false, as the illusion occurs on the open plains and the ocean! _SideNote_ Did you know that Constellations can also demonstrate this illusion? One I see a lot is Orion, check it out next time big man is rising at night! @Nicole Ball - The combined effect of the Sun and Moon's gravity on the Earth's oceans causes the tide,to be greatest when the Moon is either New or Full. At lunar perigee the tidal force is even more powerful, resulting in greater high and low tides, but even at its most powerful the force is still weak. Remember, tidal force follows an inverse-cube law, so the super-moon tidal force is about 17% greater than average. However, because the actual amplitude of tides varies around the world, this generally will not translate into a direct effect on them. So, yes the super moon does effect tides, because thats what the moon does :) but it doesnt cause storm surges, earth quakes or eruptions. You can blame earth for those!
Jaimie Cura (Editor) May 04, 2012 at 09:53 PM
Jeff, thank you for commenting and sharing your knowledge! Also, I'm going to post an article soon asking for folks to send in their super moon pics. I know we've got some talented readers and I'm just hoping for clear skies!
Aaron Turner May 04, 2012 at 09:56 PM
Thanks for the comment Jeff. I try to stick to facts as best I can, though facts may lead to dispelling a good bit of "common knowledge", sometimes even in the science community. And thanks for the assist with the tides - I was reluctant to lengthen the post with the explanation, but you have it right.
Jeff Dupuis May 04, 2012 at 10:56 PM
@Jaimie Cura - Always my pleasure to share a little science! And I can't wait to see what kind of pictures turn up! I have a horrible time photographing the full moon, generally getting just a giant white glowing orb with no features. A photographer I certainly am not! lol... @Aaron Turner - I hear you there about facts dispelling common knowledge, even in the science community; but that in itself is the beauty of science. Its not a permanent set of facts, its forever changing and advancing as new methods, theories and experiments bring forth new empirical data! I was also drawn to your post on your bio description, Amateur Astronomer and Aerospace Engineer. I myself have a deep love of the night sky, and am also involved in the Aerospace sector, being a CNC machinist by trade. I hope to see more posts from you, spread the knowledge! And always send it down to the younger generation of thinkers. They are the future and they must be inspired! (the lack of inspiration in science and technology today by the general public saddens me quite often)
CW May 04, 2012 at 10:56 PM
Thanks for the crash course Aaron. I find information ( both factual and folkloric )about the moon very interesting. I also feel we are effected bt the changes in the moon and the tides and such, I know my animal companions are. I'm crossing my fingers for clear skies too, won't promise any photos, just like to see it as this is something completly new to me this year.
Jaimie Cura (Editor) May 05, 2012 at 12:48 AM
I too can't promise any good photos either, but I can probably promise some glowing white orbs as well! :) Charlotte, I definitely believe the moon impacts behavior although I know some people disagree. We did an article on that very notion a while back, with a poll asking if the moon has an impact on folks: http://woodbury-middlebury.patch.com/articles/first-full-moon-of-2012-rises-tonight-wolf-moon-moon-after-yule-old-moon-does-the-moon-impact-human-behavior
Sandi May 05, 2012 at 02:08 AM
Are all "Super Moons" orange/red in color?
Christopher B. Carveth May 05, 2012 at 11:56 AM
In the interest of language, given the excellent science posts, the perigee moon affects tides, the effect of which is occasionally apparent.
Aaron Turner May 05, 2012 at 12:31 PM
@Sanda - The Super Moon looks just like a regular full Moon, only larger and brighter. When rising, any Moon tends to look orange or red. You may be thinking of a lunar eclipse (moon passes through the shadow of Earth) when the full moon definitely looks orange or red.
Aaron Turner May 05, 2012 at 12:39 PM
@Sandi - sorry about the misspelling. Blaming the IPod @Christopher - yes perigee increases the tides every month, and when perigee coincides with the full or new moon, the tides are very slightly increased because of the alignment of Earth, Moon and Sun. But local variability in the tides makes the Super Moon effect not readily noticeable.
thomas May 05, 2012 at 06:10 PM
the heathen will be going bonkers tonite especially at the bars, the police blotter and madhouses will be rockin.
Jeff Dupuis May 06, 2012 at 02:25 AM
I just realized tonight is the Eta Aquariids meteor shower peak (3am, constellation Aquarius). Very eventful sky tonight! While gazing, see if you can find Mars and Saturn. The meteor shower will probably be a wash due to the brightness of the full moon, and this certain shower generally yields a peak of 35 meteors an hour which isn't that much to begin with. Oh yeah... also a wash because of all the dang clouds!! *shakes fist* Can't see anything tonight!!! LOL
Jaimie Cura (Editor) May 06, 2012 at 05:39 PM
I was looking up at the sky at 4 a.m. and alas, saw no meteors! The moon came out from behind the clouds briefly and I got some less than super pictures of the super moon. I'll post them on the article and add the link here, but don't get too excited, folks! :)
C.S. May 06, 2012 at 06:09 PM
It was too cloudy to actually get a good shot at the super moon.
Jaimie Cura (Editor) May 06, 2012 at 06:11 PM
Definitely - I was also attempting this without a good zoom lens and tripod, so there were so many odds against a good photo! At any rate, I did upload the pic to the gallery but know I can do better in the future! :) http://woodbury-middlebury.patch.com/articles/super-moon-saturday-night-add-your-photos-2964ad58#photo-9800752
Jaimie Cura (Editor) May 06, 2012 at 06:12 PM
The photo I took is the very last one in the article, not the first three absolutely gorgeous photos.
Jeff Dupuis May 06, 2012 at 06:16 PM
@Jaime Cura - I like your picture, it's very dramatic with the clouds glowing in the Moon shine like that. I gave up early, frustrated by the clouds (and an early morning for work sunday). Never saw the moon once!
Jaimie Cura (Editor) May 06, 2012 at 07:29 PM
Thanks Jeff - it was a balancing act, trying to steady my hands on car roofs and anything else stable I could find. This was very early in the morning Sunday and about a half an hour later, the moon hid behind the clouds again! There's always the next super moon!
Aaron Turner May 06, 2012 at 11:57 PM
Well, that's kind of how it goes in Connecticut with astronomy events - more often than not, it seems, we miss the show. I did notice very late last night that it was unusually bright out - perhaps the moon was out of the clouds, but I was too tired to bother checking, rolled over and went back to sleep. Tonight, on the other hand, looks very promising if I can get out there later.


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