One clock, any face
A Sidereal Clock is a live display, so the same clock can wear any of these faces, and new faces can be added over time. Every face shows the same real sky and the same Crux hand, on standard time all year, and on the Northern faces the Southern Cross can be shown on the hand or switched off. What changes is how the time and the months are laid out for you to read.
The golden rule, on every face
At midnight, the Cross points to the month. The hour and minute hands tell the time; the Crux hand, the long needle through the Southern Cross, tells the sky. Learn that one rule first, and each face below adds a different way of seeing it.
Five mirrored pairs
Each pair below is a matched set, one clock for each end of the Earth, or one for each side of the glass. Every face on this page is live, and all of them keep standard time.
1. The Twin Clocks
The original pair. The Crux Movement is a normal twelve-hour clock over the live southern sky, with the Crux hand running from the south celestial pole through the Southern Cross. The Northern Movement is its exact mirror: the northern sky turns anticlockwise around Polaris, and the numerals, time hands and month ring are mirrored to match.
How to read them. On both, at midnight the Crux hand points to the month on the ring. Through the night it moves about one number every two hours; at the same time each night it moves on about one number a month, clockwise in the south, anticlockwise in the north.
2. The Bezel Twins
How they work. The months move to an outer bezel that turns with the Crux hand but falls about ten dial-seconds behind each day: exactly one turn per day. The hand gains one month on the bezel each month, so it is always pointing at today’s date.
How to read them. Follow the Crux hand and its dotted line out to the bezel: that is today’s date, at any hour of the day or night. At midnight each bezel is back home, with April at XII, exactly like pair 1.
3. The Clockwise Twins
How they work. Both clocks tell the time the same way, with clockwise numerals and hands. Only the skies differ: the southern sky turns clockwise around the south pole, the northern sky anticlockwise around Polaris, so the Northern Crux hand and month ring run the other way.
How to read them. Read the time as on any clock. At midnight the Crux hand points to the month; on the Northern face it walks backwards against the numerals, XII, XI, X through the night and one number back each month.
4. The Clockwise Bezel Twins
How they work. Pair 3 with the turning month bezels of pair 2: familiar clockwise time on both, and on each face the Crux hand pointing at today’s date on its bezel at any hour.
How to read them. Read the time as normal, then follow the Crux hand’s dotted line to the bezel for the date. The southern bezel turns clockwise, the northern anticlockwise.
5. Through the Glass
How they work. The same southern sky from both sides of the glass. The mirrored face is the Crux Movement as it would look from behind: the Southern Cross, the stars, the numerals and the hands are all reversed, while every label stays readable. It suits a clock set into glass, a window or a partition wall seen from both sides.
How to read it. Every rule of the Crux Movement holds, turned anticlockwise: at midnight the Crux hand points to the month.
The Northern hands switch
On the Twin Clocks the Southern face stays as it is, and the Northern face can be set to mirrored or clockwise hands.