The Moon

If you look to the right hand panel on this page, you should see a link to the Astronomy Picture of the Day - one of the places I go every day for a fix of fascinating pictures of the universe around us.

I must say, however, that today's picture is even more fascinating than usual. It shows the last 20 full moons in a mosaic (and links to a movie version too!), with all the images to the same scale. It demonstrates that the apparent size of the Moon really does change over time, as the mutual Earth-Moon orbital system varies. Actually, the mosaic takes some examination to see this effect, but movie is much clearer.

I knew that the distance between the Earth and the Moon varied, but I've never seen it presented so graphically before.

If you like this one, you should also try the one from 28th December 06 as it also shows the Moon, but to the same angular scale (size in the sky) as the Andromeda Galaxy. Normally the galaxy is much, much fainter than the Moon, so this kind of image can only be seen in composite, but I'd never realised just how large a galaxy like Andromeda is when viewed from the shared viewing platform we call the Earth.