Radio waves around the world travels strange ways sometimes.
So what is the best time (and wavelength) to use if I want to make a JOTA contact with another scout station far away?
You can all find it here.
Just click on the interactive map from which point you are transmitting and which continent or country you want to reach. The calculator gives you the best time to make the connection. Ask your radio amateur for help with some of teh technical details on transmitter power and antennas.