When is dawnrise during polar night?

Several rules in the Buddhist Monastic Code depend on exact definitions of dawnrise (and noon). As an example, Pācittiya 37, which is the basis of the sixth precept, states: > Should any bhikkhu chew or consume staple or non-staple food at the wrong time, it is to be confessed. Where the "wrong time" is between noon and dawnrise of the next day. Both noon and dawnrise seem to be defined by the position of the sun in the sky. However, in the far north, [polar night](https://en.wikipedia.org/wiki/Polar_night) means that some places go months without dawn in the winter. What do monks do in this situation? Surely they don't go that long without eating.