I can't believe I was {HOWEVER OLD I AM NOW} when I learnt that the Moon is 'upside down' when seen from the Southern Hemisphere. I mean, of course it would be - but I'd never made that deductive leap.

Made me feel like a fool, especially given I made my at-the-time pregnant partner crease her nose in not-quite-credulous but also sorta-believing suspicion when I told her that the Japanese don't see a Man in the Moon, rather a Rabbit, because on that side of the Earth they see the opposite side of the moon. I could only maintain the pretense for a few minutes before she scolded me :)