Why does the moon appear bigger sometimes?:rolleyes:

Its an optical illusiuon of sorts. There is no real explanation right now, as many scientists have different opinions. Some say it has to do with objects we are comparing it to (ie: trees, buildings, etc... some say it has to do with the refraction of our atmosphere) but if you take a picture with a cmaera, it will appear the same size regardless of how you viewed it. One of the many amazing optical illusions humans see.

why does the moon appear bigger sometimes?:rolleyes:
It's is an optical illusion.

When the moon is high in the sky, it's a) travels through less of the earth's atmosphere and thus appears brighter and harder to make out detail and b) without other subjects around such as trees or houses, there is no way to judge scale. When the moon is near the horizon, its light has to travel through more of the earth's atmosphere and hence appears dimmer and more detailed giving it the impression of being closer.