Classes and test classes for computing planetary positions. The classes can be instantiated by calling new: aDayNumber withLatitude: aLatitude withLongitude: aLongitude atUTC: aUTC. eg. Sun new: -3543 withLatitude: 60 withLongitude: 15 atUTC: (0)*15. The day number is an instance of TimeScale and the time in UTC must be converted to degrees by multiplying by 15.