Big Moon, Small Moon

One of the RSS feeds i am subscribed to on my Google Start Page is science@NASA which told me to be on the look out on the 10th of January (2009) for the full moon that is "fuller" than usual. The Moon orbits the Earth in an elipse, and it happens to be at perigee - it's closest point, so looks a lot larger.


It looks even larger when rising or setting. Now I say it looks a larger... this is an illusion created by our brains... not by the atmosphere or our eyes. You can measure it's angular size near the horizon and when it is at it's zenith and your measurements will be the same, so the cause is an optical illusion. For an explanation of this trick of the eye, read this.