30 June 2014

Moon at Apogee

We end the month of June with Moon being farthest to earth today, 30/06/2014 at a distance of 4,05,932km. The 3-day-old crescent moon will be an amazing site in the evening twilight. After sunset crescent moon will be high in the western sky at an altitude of 30degrees and will set at 9pm.

Graphic: Stellarium 

Moon orbits the earth with an eccentricity of 0.0549, not a circle, and that makes moon to have farthest and closest points from earth.  Apogee is when Moon is farthest from earth and Perigee is when moon is closest to earth.

Moon on 30th June will be at Apogee at a distance of 4,05,930km from earth with an angular diameter of 0.49degrees.  As moon continues in its orbit, it will reach closest point to earth, Perigee, on July 13th at a distance of 3,58,260km and this will make the angular diameter of moon 0.55degrees.

As we can see, the difference is too small to be observed without any reference, best way to measure this difference is to take photographs of moon at Apogee and Perigee and compare the prints. Today if the skies are clear in the evening sky, go out and enjoy the crescent moon.