Partway through Winter in Hieron, an extended eclipse takes place in which the sun is blocked by Del and Bri, the two moons of the skies over Hieron. Much like the wintry weather from the Seasons of Hieron Holiday Special, what started as a freak occurrence now has no end in sight.
The Forest Party witnesses the start of the eclipse during their initial confrontation in Old Man's Chin with the Ordennans, while the Mountain Party is inside Rosemerrow's Old Museum at the time, and emerges to see that the sky is dark.
Days seem to run in a 36-hour cycle, which can be broken down into 12-hour sections of normal darkness, dim light, and complete darkness.
It is unclear whether the days of the week are still being used during the eclipse.