Have you ever wondered about or even tried to look at the size of the Full moons in different times throughout the year? You may ask why? Moon goes around the earth in an elliptical orbit so it is not at the same distance from us all the time (as its not a circle), as a result it appears to grow and shrink (not too much) as seen in the skies (though it does not grow or shrink physically!!).
And its more apparent on the day of the full moon when we see the whole disk illuminated. Now just imagine seeing a bigger full moon - it means that moon is at perigee (point nearest to earth) or near perigee at that time. As its a bigger moon then there has to be a name to it as we humans are very much inclined towards giving names to each and every thing!! They call it SuperMoon!! And this word was coined recently in late 70’s(if we talk about time scales in astronomy).
And its interesting to know that SuperMoon is a word which was not coined by astronomers but by an astrologer , Richard Nolle, who is credited with coining the term supermoon. He arbitrarily defines this as
. . . a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth. But for us its the Perigee full/new moon happening at the exact time of perigee so there is no ambiguity about the definition. Now our new definition becomes - . . . a new or full moon which occurs with the moon at its closest approach (perigee) to Earth. The technical name is the perigee-syzygy of the Earth-Moon-Sun system. We astronomers do not use the term “Super Moon” but to take it among the masses its a catchy word! As we have Supermoon, there has to be Micromoon which happens at Full moon at the time of Apogee. And if you happen to click both the moons with same setup, you would find a drastic change in diameter which is around 14% and thats quite large!!
Now lets see how many Full Moons fit into this definition. We have not taken New Moon in this category as it can't be seen at all!!! But a supermoon at new moon at the time of the eclipse play a different game, that i leave to you people to ponder.
In present century we have the following SuperMoons which fit in the definition of Full Moon and Perigee moon happening exactly at same time (Perigee happening at F +/- 0 h):
2011 356577 km 3/19/2011
2012 356953 km 5/6/2012
2013 356989 km 6/13/2013
2014 356896 km 8/10/2014
2034 356447 km 11/27/2034
2054 356511 km 1/24/2054
2073 356720 km 5/23/2073
2094 356867 km 8/26/2094
2095 356685 km 10/13/2095
There are quite a lot of more so called supermoons if we relax our stringent rules to allow for few hours +/- difference between Full Moon and Perigee Moon
We come back to our discussion about supermoon again. You can see that there is one supermoon coming on 10th August 2014. So what big deal about it? Well On that day the Full Moon will be approximately 14% bigger than the Full Moon on Apogee and will be 30% more brighter than it. If you plan to click the image on that day then make sure that you click with same setup another image on March 5th next year when we have the Full Moon happening near to Apogee and then you can actually calculate the difference we have talked about. Above Image is an example which we did in 2011. And interseting when you see the above image and the once you will take, you will see the phenomenon which we call as liberation of the Moon, well that's another story to tell!!!! But Do enjoy the illuminated Moonlight dinner on that night with your near and dear ones!!
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