can't initialize a constant using another constant?

Dear list,

Quite some time since I wrote. I hope you are all keeping well. :)

A strange thing I ran across this evening. I was not allowed to do:

const double lunarSynodicMonth = 29.53059 ;
const double daysLunarPhaseAngleTakesPerDegree = lunarSynodicMonth / 360.0 ;

I got the following error:

wdf-karanas.c:17: error: initializer element is not constant
make: *** [wdf-karanas.o] Error 1

I would be grateful if anyone could shed some light. TIA.

Shriramana Sharma.