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| Images of the Solar Disc (photosphere) and the full Moon. Seestar S30 from the JPO Image credit: Kurt Thrust. |
"The Sun and the Moon appear to be the same size in the sky, when viewed at the same altitude. If they didn't, a total solar eclipse would not happen when they align in sky. The Moon would be unable to fully cover the solar disc and an annular rather than full eclipse would occur..
In reality the actual diameter of the Solar disc is x400 that of the diameter of the Moon. At this period in time, the Sun is x400 further away than the Moon and that is why they appear in the sky as the same size.
The Moon is slowly moving further away from the Earth at 3.8cms per year. This is the same rate at which human fingernails grow.
The Moon is moving away from the Earth because of a transfer of gravitational energy from the Earth to the Moon. The Moon acquires kinetic energy, its orbital velocity increases and its orbit lengthens requiring the Moon to move further away to maintain dynamic equilibrium. Similar gravity transfers of energy between the Earth, the planets and space probes in orbit are used to propel the spacecraft on longer elliptical journeys to other planets in the Solar System.
It is thought, that last total solar eclipse, due to the Moon' moving further away from the Earth, will happen in 650 million years time. So astro-punters, no need to hurry on the eclipse chasing front!
The next time you look at the Moon, check whether you need a manicure, 'wink' and think of Neil.
For fun and giggles, Pip Stakkert created a 'faux partial eclipse of the Sun' to wile away an hour on a Bank Holiday afternoon". - Joel Cairo CEO of the Jodrell Plank Observatory.
