One hand, two readings
The Cross acts as the hand. Sidereal motion gives the hour, while the monthly drift lets the same ring act as a calendar.
The Crux Perpetual
A developing Southern Cross clock-calendar where Crux is the hand, the South Celestial Pole is the pivot, and one sky movement reads both hour and month.
Newest CalculationTime tool
The Crux Perpetual
We are proud of how far this instrument has developed. It began as the Southern Cross Clock and is now becoming a clock-calendar: the hour from the sky's rotation, the month from the sky's drift, and both read from one hand around a pivot that does not need winding, signal or correction.
This is still a developing instrument. Please help by reporting bugs, broken controls, mobile problems, confusing labels, or any sky-reading detail that does not match what you observe.
Interactive instrument
Build D6: Billy-approved Crux Perpetual
Development notes
What changed from the Southern Cross Clock
The historical Southern Cross Clock remains intact. The Crux Perpetual is the next development lane: dynamic month-ring synchronization, a real galactic-plane Milky Way layer, named structures, and a clearer clock-calendar identity.
Real sky context
The Milky Way layer is computed from galactic coordinates, with the Coalsack and named structures kept as sky features, not decoration.
Bug reports welcome
Controls, mobile fit, sky labels, month behavior and source notes are all worth testing while this tool matures.