Geriatric OE

The weekly musing of a couple of Kiwis on their geriatric OE in The UK






Friday, 20 December 2013

A moon by any other name..is still a moon



If the sky was clearer we would be able to see the full moon. Did you know that not only is it the last full moon of the year it is also the smallest full moon of the year as well.
Apogee and Perigee of the Moon
Apogee and perigee refer to the distance from the Earth to the moon. Apogee is the farthest point from the earth. Perigee is the closest point to the earth and it is in this stage that the moon appears larger. Looking at the moon in the sky without anything to compare it to, you wouldn't notice any size difference. But the difference in size can in fact be quite significant.
If you were to photograph a full moon at apogee and perigee (using the same lens), here's how the two sizes would compare:


Effects of Apogee and Perigee
The apogee and perigee of the moon have an effect on the tides here on Earth. When the moon is at apogee, the furthest distance from the Earth, it has less gravitational pull which, along with other factors that influence the tides, can contribute to lower tides or lower variation in the high/low tide level. When the moon is at perigee, closer to the Earth, there is much more gravitational pull which contributes to the opposite effect: higher tides or greater variation in the high and low tide.

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