Equator

When on Lake Toba I noticed that the Sun behaves "oddly" - to follow it during the day I have to be turning anti-clock wise, not clock wise like I was doing it my whole life. Aha, I thought, that is what you get when you are below equator - except that I was not, I was still a couple of degrees above it.
I looked into it and learned the relevance of Tropics of Cancer and Capricorn, I was aware of their existence and the place on the map of Earth but did not know what they were all about. Now I do :)

If you are curious - click on Wikipedia article.

Now that I am below equator - at night I see above me Southern Cross, not Big Polar Bear.