Super Moon 3-2=1

 Graphic Credit: Heart Touching Fun (red-lined by me)

Graphic Credit: Heart Touching Fun (dates red-lined by me)

   File this under the ‘here we go again’ once again, again. Three “Super Moon” ‘events’ in a row starting with the full Moon of this past July 12th; then again on August 10th; and then again with this one on September 9th. I am hoping that this graphic will help in putting my thoughts into context. Meaning exactly how big is a Super Moon compared with other full Moons, and will it really be noticeably larger?
   According to this graphic which was on Facebook about a year ago the full Moon of 23 June 2013 would be the largest appearing one of that year as well as the closest one for that year – a “Super Moon”. While the part about closest and largest appearing is correct, using the term “Super Moon” is misleading in the sense that there is nothing for comparison and so there will be folks going outside expecting to see a really large appearing full Moon? But how large? As large as the banner graphic suggests!!
sci-ence_neiltyson_moonillusion   So what is a “Super Moon”; how “super” is it in comparison to other full Moons. And how significant, if at all, is this ‘event’?
   A “Super Moon” is a full Moon that occurs very near to its time of perigee, the closest the Moon comes to the Earth for that particular orbit, or month. By definition, “very close” would be when the Moon is less than 10% of its orbital period (about 2.9 days to 3.2 days) from the time of perigee. Use the data in the table below to compare the full and new Moon dates, with the apogee (farthest) and perigee dates and distances. Dates for apogee and perigee are given showing how many days and or hours before or after the date of the new or full moon these two distances occur.
   Here is an idea – use the apogee dates to determine when we will have a “Super Mini-Moon”!

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   By comparing the dates and distances for this year, you will see that there are several “Super Moon”s in 2014. In fact, each year there are from four to six occurrences when the full Moon and perigee are close enough to be considered a “Super Moon” – the full Moon closest to the time for perigee is the actual “Super Moon” for that year. So a “Super Moon” is not that unique nor worthy of the hype these next three will receive other than drawing people’s attention to the night skies and our closest natural solar system neighbor.
   Carry this analysis further by comparing dates for full Moon and perigee over a several year period, and you’ll find a pattern in the regularity of “Super Moon” events. How? There are two regular time periods, or cycles, involved in the pattern for “Super Moon”. First, the time period between each full Moon, the synodic month, is approximately 29.53 days; second, the time period between each perigee, the anomalistic month, is approximately 27.55 days. With a two-day difference between these two cycles, there is obviously not a super Moon every month. However, with a ratio of 14 synodic months to 15 perigee periods,the closest of the “Super Moons” to perigee will occur about every 13-14 months. Because of the ratio relationship between these two cycles, 14 full Moons after the full Moon of June 23, 2013 (356,989 km), there will be the closest full Moon of 2014 on August 10th (356,896 km), which will be followed by the closest full Moon of September 28, 2015 (356,877 km), and so on.

   The above has been adapted from my October 2012 Scope on the Skies column in Science Scope Magazine “Apparent Sizes, or It Was This Big”. Click here to download a copy of that column (PDF).

   Before you look at the data tables below here are some ‘Super Moon’ pictures and graphics I collected from around the web. Since most of the pictures are of a rising or setting Moon and there are objects in the foreground this creates an optical illusion where the Moon appears to be quite large. I think that folks see the Moon as in these pictures and are convinced that they have indeed seen a ‘Super Moon’ – when in fact they have not.
Prove the Moon Does Not Change Its Size:
   To help correct this idea or to prove to yourself that the Moon is not bigger when it rises or sets look at the Moon through a toilet paper tube or something similar when the Moon is near the horizon and then a couple of hours later when it is higher above the horizon. The Moon is same size on both sightings.

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 (N=New Moon; F=Full Moon '-' = before; '+' = after)
           2014 - All times are shown in UT (Universal Time)
             Perigee                            Apogee
---------------------------------   ---------------------------------
Jan  1 21:01 356921 km -  N+   9h   Jan 16  1:54 406536 km +  F-   2h
Jan 30  9:59 357079 km -  N-  11h   Feb 12  5:11 406231 km +  F-2d18h
Feb 27 19:53 360438 km    N-1d12h   Mar 11 19:47 405365 km    F-4d21h
Mar 27 18:31 365705 km    N-3d 0h   Apr  8 14:53 404501 km    F-6d16h
Apr 23  0:28 369764 km    N-6d 5h   May  6 10:23 404318 km    N+7d 4h
May 18 11:59 367098 km    F+3d16h   Jun  3  4:26 404955 km    N+5d 9h
Jun 15  3:35 362061 km    F+1d23h   Jun 30 19:11 405931 km    N+3d10h
Jul 13  8:28 358258 km    F+  21h    Jul 28  3:28 406568 km -- N+1d 4h
Aug 10 17:44 356896 km ++ F-   0h   Aug 24  6:10 406522 km -  N-1d 8h
Sep  8  3:30 358387 km    F-  22h   Sep 20 14:23 405845 km    N-3d15h
Oct  6  9:42 362480 km    F-2d 1h   Oct 18  6:06 404897 km    N-5d15h
Nov  3  0:22 367870 km    F-3d22h   Nov 15  1:57 404336 km    N-7d10h
Nov 27 23:12 369824 km    N+5d10h   Dec 12 23:04 404583 km    F+6d10h
Dec 24 16:44 364790 km    N+2d15h   

Data Table Source: Lunar Perigee and Apogee Calculator.

2014 Lunar Phases — Using U.S.A. Central Time (UT-6 or UT-5) 
      New Moon	           Full Moon	            
Jan. 1 We. 05:15 AM	Jan. 15 We. 10:53 PM	
Jan. 30 Th. 03:40 PM	Feb. 14 Fr. 05:54 PM	
Mar. 1 Sa. 02:02 AM	Mar. 16 Su. 12:10 PM	
Mar. 30 Su. 01:48 PM	Apr. 15 Tu. 02:45 AM	
Apr. 29 Tu. 01:17 AM	May 14 We. 02:18 PM	
May 28 We. 01:43 PM	June 12 Th. 11:13 PM	
June 27 Fr. 03:10 AM	July 12 Sa. 06:26 AM	
July 26 Sa. 05:42 PM	Aug. 10 Su. 01:10 PM	
Aug. 25 Mo. 09:13 AM	Sept. 8 Mo. 08:38 PM	
Sept. 24 We. 01:13 AM	Oct. 8 We. 05:50 AM	
Oct. 23 Th. 04:56 PM	Nov. 6 Th. 04:22 PM	
Nov. 22 Sa. 06:32 AM	Dec. 6 Sa. 06:27 AM	
Dec. 21 Su. 07:36 PM			    

Source of Lunar Phase Data: Moon Phases.

Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

1 thought on “Super Moon 3-2=1

  1. Pingback: September Perigee Moon Is the 3rd Super Moon | Bob's Spaces

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