Surprisingly easy for religious Jews. Sunset today? It's Friday so that's around candle lighting time. Full moon? We are just over halfway through the Adar I lu

Surprisingly easy for religious Jews. Sunset today? It's Friday so that's around candle lighting time. Full moon? We are just over halfway through the Adar I lunar month. North? Easy if you pray towards the east. I also live in a city (London) whose y and z coordinates are both approximately 0, which keeps things simple, although it's quite possible that the answer to 'where does your waste go' is the Thames.