Home Search GeoAstro Applets Astronomy Mac Programs Chaos Game Java Miscel- laneous Physics Quiz Who is Who ?

The Full Moon during the year

(location: Berlin at 51.5° N, 13.4° E, year 2000)

 Month GMT Elev. Jan 20 23:03 57.1° Feb 18 22:44 53.2° Mar 20 23:58 36.9° Apr 18 23:23 29.2° May 18 23:37 19.2° Jun 16 23:09 15.7° Jul 16 23:31 15.9° Aug 14 23:03 19.6° Sep 12 22:30 25.5° Oct 12 22:41 37.9° Nov 10 22:07 45.9° Dec 10 22:35 56.5°

The movie shows the transit of the full moon over the year. Did you notice that the elevation above horizon is much grater during winter than it is during summer ? The maximum values occur in December (56.5°) and January (57.1°), the minimum values in June (15.7°) and July (15.9°). What is the reason ?

 Summer An observer is located at O in the northern hemisphere (latitude 50°). In the northern summer the north pole NP is inclined towards the sun. At noon the (red) elevation angle of the sun is: 90° - 50° + 23.5° = 63.5° The orbit of the moon has only a small inclination against the ecliptic plane (5.5°). So the moon can be assumed to be in the ecliptic plane of the sun. Until midnight, the earth turned the observer by 180° to the opposite side. The elevation angle for the full moon (blue) is: 90° - 50° - 23.5° = 16.5° Winter Half a year later (winter) the earth has moved half around the sun in the ecliptic plane. As the inclination of the earth's axis remains constant the north pole is now away from the sun. At noon the (red) elevation angle of the sun is: 90° - 50° - 23.5° = 16.5°   At midnight, the earth turned the observer by 180° to the opposite side. The elevation angle for the full moon (blue) is: 90° - 50° + 23.5° = 63.5°

Moon Phases

The Waxing Crescent Moon

Location: Berlin at 51.5° N, 13.4° E.

Spring (April 7, 2000) at 18:25 GMT, shortly after sun set, the moon is quite high and inclined.

Autumn (September 30, 2000) at 18:25 GMT, shortly after sun set, the moon is low and upright.

The overlay. The blue curve is the celestial equator.