Kane woke up at the first sight of dawn, when it was still too early for most of them. How did she know it was dawn when they were underground? Because of the dial on the head of the room that pointed towards the sun.
It was a device that resembled the ancient days of clocks for humans and while the upper half resembled morning, the lower half resembled night. At the topmost there was a small circle denoting sun which meant it was at the highest peak during the day. The time when it's so hot, even the underground can feel it.
To balance it off it would have been nice if on the opposite side there would have been a moon, but the thing with Watron is that there was no moon. The night would be pitch dark if Watron didn't have segments. The blue sun created multiple reflections on the other segments giving a nice halo in the night that works as a part of reflection from the segments.