MOON WATCH NIGHT: The Moon Illusion

You will need to be able to see the Moon shortly after it rises, or shortly before it set and have a clear horizon.

This can be done on any night, but is better the closer you get to Full Moon.

Notice how big the Moon appears to be compared to objects on the horizon.

Now let’s see if it really is bigger than normal:

· hold your little finger out at arms length and cover the Moon – what fraction of your finger width does the Moon cover – ½, ¾ ?

· now take a look at the Moon later in the night, when it is higher in the sky and further from the horizon.

· does it look bigger or smaller to your eyes?

· ok let’s prove it – hold your little finger to cover the Moon – again what fraction is covered

So if the Moon has not changed in size relative to your little finger, then this is because the so called Moon Effect is psychological, namely the Moon looks bigger if seen along the line of sight, next to distant objects.

Moon rise times (BST) in the UK for Oct 12^th - remember to look in the east - N.B. this will be in daylight and difficult to see:

London	14:59
Birmingham	15:10
Cambridge	15:00
Cardiff	15:12
Edinburgh	15:29

Moon at its highest (due south) in the UK at:

London	19:44
Birmingham	19:51
Cambridge	19:42
Cardiff	19:57
Edinburgh	19:57

Moon set times (BST) in the UK for Oct 13^th - remember to look in the west:

London	00:28
Birmingham	00:33
Cambridge	00:25
Cardiff	00:42
Edinburgh	00:26

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Webmaster: Dr Anthony Cook

Web version 2013/10/11

(Email: atc @ aber.ac.uk)