Noon moves.
Today, from Greenwich, the sun crosses your meridian at 12:07:22. Your clock rounded that off a century ago and never mentioned it.
Two errors, added.
The Earth leans, and its orbit is not a circle. Neither fault is large. Together they move noon by half an hour.
The leanThe axis is tilted 23.4°, so the sun's apparent progress along the horizon speeds up and slows down through the year. This curve runs from −9.9 to +9.9 minutes and does it twice.
The ellipseThe orbit is not circular, so the Earth travels faster in January than in July. One slow swing a year, −7.1 to +7.1 minutes.
The equation of timeAdd them. The sum reaches +16.5 minutes on 3 November and −14.2 on 11 February. Your clock ignores all of it.
One year, one line.
This is where the sun stood at 12:00, from Greenwich, on every day of 2026. Three hundred and sixty-five readings, and it closes. Change the latitude at the foot of this page and it is redrawn — this is a calculation, not a picture of one.
The shadow is the readout.
Angle gives you the hour. Length gives you the season. The dotted curve is today's declination line — the path the shadow's tip takes from sunrise to sunset — and it is a different curve tomorrow.
Cut for one latitude.
Tell us where it will stand and the hour lines are computed for that parallel. A plate made for 51° reads twenty minutes wrong in Madrid, so we will not sell you one.
| Material | Sand-cast phosphor bronze, hand-finished, left to patinate |
|---|---|
| Diameter | 180 mm |
| Gnomon | 60 mm, cut to the latitude you give us |
| Graduation | 0.5° divisions, engraved |
| Analemma | Engraved on the noon line, for correcting clock to sun |
| Reverse | Your latitude and longitude, and the year it was cut |
| Lead time | Eleven weeks |
Tell us where it will stand.
Every plate is engraved for a single parallel. The figure above is already yours.
TRUE NOON · Plate No. 4 · 51.4779° N · Greenwich · next solar noon 12:07
Sun positions computed in your browser with the NOAA solar position algorithm. Nothing on this page is a photograph.