The Astronomy of Darkhold
Darkhold has two moons, an inner one known as "Rabbit", and an outermoon, known as "Tortoise". The inner moon has a cycle of seven days, which defines the week, and the outer has a cycle of 28, which defines the month. They are synced in period so that once every 28 days, both moons are full at the same time.
Rabbit is silver-grey in appearance, with cratered features which can easily be distinguished. Tortoise, however, is pale green and shimmery, containing what is probably an atmosphere.
Darkhold has a calendar of 12 months, each of 28 days. The year starts on Midsummer's Eve (which is also known as New Year's Day), with a double eclipse of both moons. The names of the months are (in common/Elvish): New Hope/Newyth; Fire/Tawn; Golden Time/Aur Amser; Harvest/Medi; Fire Seek/Tawnoisho; Ice/Rhew; Land's Death/Tiriamga; Sun's Return/Hologem; Wanting/Angenyth; Rebirth/Atgyvodiad; Planting/Plannew; and Green Peace/Glastangneveth.