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In this issue of Math in the News we investigate the Super Moon phenomenon mathematically. For more math media resources, go to http://www.media4math.com.
Citation preview
Learn more about the Super Moon phenomenon. Watch this
YouTube video. http://youtu.be/kOplwuMTyS4
The Super Moon
The Moon’s elliptical orbit around the Earth makes it closer to Earth at its perigee and farthest from Earth at its apogee.
The Super Moon
This table shows the distance from the Earth to the Moon throughout 2012. Notice how the distances vary, reflecting the changes from apogee to perigee.
Date Distance (km)2-Jan 404589
17-Jan 36989930-Jan 40432511-Feb 36792827-Feb 40484210-Mar 36240826-Mar 405744
7-Apr 35832422-Apr 4064315-May 356964
19-May 4064393-Jun 358491
15-Jun 4057961-Jul 362366
13-Jul 40479329-Jul 367310
10-Aug 40412223-Aug 369740
7-Sep 40430318-Sep 365759
4-Oct 40518316-Oct 3606601-Nov 406066
14-Nov 357356
The Super Moon
To graph the data let’s convert the dates to numerical values. January 1 is assigned 1 and December 31 is assigned 360. We can now graph this as a scatterplot.
Date Distance (km)2 404589
17 36989930 40432542 36792858 40484270 36240886 40574498 358324
113 406431126 356964140 406439155 358491167 405796183 362366195 404793211 367310223 404122236 369740251 404303262 365759278 405183290 360660306 406066319 357356
The Super Moon
The graph of the data shows how the distance from the Earth to the Moon is periodic.
The Super Moon
We can modify the data to make it easier to graph. The average distance from the Earth to the Moon is 384483 km. Let’s rescale the data using this formula:
Date Distance (km)2 404589
17 36989930 40432542 36792858 40484270 36240886 40574498 358324
113 406431126 356964140 406439155 358491167 405796183 362366195 404793211 367310223 404122236 369740251 404303262 365759278 405183290 360660306 406066319 357356
The Super Moon
Here is the rescaled data.
Date Distance (km)2 2.0186
17 -1.450430 1.992242 -1.647558 2.043970 -2.199586 2.134198 -2.6079
113 2.2028126 -2.7439140 2.2036155 -2.5912167 2.1393183 -2.2037195 2.039211 -1.7093223 1.9719236 -1.4663251 1.99262 -1.8644278 2.078290 -2.3743306 2.1663319 -2.7047333 2.1963347 -2.7319360 2.1691
The Super Moon
Here is the graph of the rescaled data with the Super Moon highlighted.
The Super MoonThe reason that a Super Moon is so rare is that the periods for the phases of the Moon and its orbit differ by about two days. These graphs show how they quickly get out of phase, and it takes many periods for them to intersect. Super Moons happen about once a year.
The Super Moon
Do you plan on watching the next Super Moon?