Misc: By what name is the 2nd day of February called in the U.S.A.?

Questions

Optics - What colour on black produces the most visible combination?

Orienteering - On maps, what is the technical name for the 'you are here' arrow?

Philosophy - The last line of which document is 'working men of all countries, unite!'?

Physics - At what angle above the horizon must the sun be to create a rainbow (in degrees)?

Physics - Waves 'break' when their height is how much more than the depth of the water?