How as an individual can I know if the Earth is a sphere or a flat disc? What experiment can I do that doesn't involve trusting information from a 3rd party that would prove what the geometry really is?
http://i.imgur.com/O8IpMmi.jpgAll you need to do is to travel to the antarctical and fly above it and look below. Physically.
Otherwise, here is some good information you can make use of.
https://www.timeanddate.com/worldclock/distances.html?n=468