Sunday, 27 July 2014

The Lunar Apogee.

On Monday 28 July, at 3.28 am GMT, the Moon will be at its furthest point from the Earth in 2014, a distance of 406 568 km. The Moon orbits the Earth every 27.5 days, and like most orbiting bodies, its orbit is not completely circular, but slightly elliptical, so that the distance between the two bodies varies by about 3% over the course of a month. This elliptical orbit is also not completely regular, it periodically elongates then returns to normal, making some perigees closer than others. Because this is an elongating and contracting elliptical orbit, rather than a change in the average distance between the Earth and the Moon, the most extreme Lunar Perigee and Apogee of each year typically happen in the same Lunar Month; this year the closest Lunar Perigee will occur on 10 August, at 3.44 pm GMT.

Diagram showing the relationship of the Lunar orbit and Lunar month. Southern Astronomical Delights.

Although this is the furthest point from the Earth that the Moon will reach in 2014, it is not exceptional. The Moon reached 406 655 km from the Earth on 2 April 2011, and will reach 406 659
 on 4 October 2016. 

See also...

The dwarf planet Pluto will reach opposition slightly before 3.00 am GMT on Friday 4 July 2014; this means that it will be directly opposite the Sun in the sky when viewed from Earth, on this occasion in the constellation...

At midnight between Thursday 3 and Friday 4 July 2014 the Earth will reach its aphelion, the furthest point in its orbit from the Sun, a distance of 152 093 481 km. The Earth's orbit is slightly eccentric and slightly variable, leading to the distance between the Earth and the Sun varying by about 3.4% over time, reaching aphelion early in July each year and perihelion (the closest


The planet Saturn will be at opposition (directly opposite the Sun) at about 6.00 pm GMT on Saturday 10 May 2014. This means that it will both be at its closest to the...

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