Astronomy explainer · polar view
The Turning Earth: Polar Clock
A single polar projection makes the midnight line, the daylight side and the Crux hand relay readable at once. Use it to see why each clock strikes zero when its own meridian reaches standard-time midnight.
Midnight made visible
The polar view compresses the globe into a clean clock face. The gold midnight line, the daylight edge and the clock ring can be read together without chasing the back of the Earth.
A relay on a dial
Each numbered clock waits for its own meridian to pass under midnight. The closer the gold line gets, the closer that clock is to its zero reading.
Best use
Use this page when the important thing is the relationship between the pole, the Sun, the night side and the numbered Crux-clock ring.
The 24 midnight-zero meridians
Each longitude is where the Crux hand reads exactly 0° at that zone’s standard-time midnight ending 31 March 2026. Latitude does not change the hand, so each place is a real spot on that meridian. The reference is Cumnock, New South Wales, 35 km due east of Parkes Observatory.
| Zone | Meridian | Latitude | Place on the meridian | Note |
|---|---|---|---|---|
| UTC−11 | 167.2231° W | 53.60° N | Unalaska Island, Alaska | No UTC-11 land on this meridian; Alaska keeps UTC-9. |
| UTC−10 | 152.1821° W | 16.44° S | Off Maupiti, French Polynesia | At sea, ~5 km east of Maupiti reef. |
| UTC−9 | 137.1410° W | 58.66° N | Mount Crillon, Fairweather Range, Alaska | |
| UTC−8 | 122.0999° W | 37.39° N | Mountain View, California | |
| UTC−7 | 107.0589° W | 38.55° N | Gunnison County, Colorado | |
| UTC−6 | 92.0178° W | 30.22° N | Lafayette, Louisiana | |
| UTC−5 | 76.9767° W | 38.90° N | Washington, D.C. | |
| UTC−4 | 61.9357° W | 16.24° S | Concepcion, Santa Cruz, Bolivia | |
| UTC−3 | 46.8946° W | 23.19° S | Jundiai, Sao Paulo, Brazil | |
| UTC−2 | 31.8535° W | 72.58° N | Greenland ice sheet | |
| UTC−1 | 16.8125° W | 28.30° N | Santiago del Teide, Tenerife | No UTC-1 land on this meridian; the Canaries keep UTC+0. |
| UTC+0 | 1.7714° W | 51.17° N | Amesbury, Wiltshire (by Stonehenge) | |
| UTC+1 | 13.2697° E | 52.52° N | Berlin (Charlottenburg), Germany | |
| UTC+2 | 28.3108° E | 25.75° S | Pretoria (Mamelodi), South Africa | |
| UTC+3 | 43.3518° E | 43.49° N | Nizhny Chegem, Kabardino-Balkaria, Russia | |
| UTC+4 | 58.3929° E | 23.59° N | Muscat (Bawshar), Oman | |
| UTC+5 | 73.4340° E | 33.90° N | Murree, Pakistan | |
| UTC+6 | 88.4750° E | 24.37° N | Paba, Rajshahi, Bangladesh | |
| UTC+7 | 103.5161° E | 13.41° N | Siem Reap Province, Cambodia | |
| UTC+8 | 118.5572° E | 32.07° N | Nanjing (Pukou), China | |
| UTC+9 | 133.5982° E | 34.58° N | Okayama Astrophysical Observatory, Japan | The observatory dome is ~350 m west of the meridian. |
| UTC+10 | 148.6393° E | 33.00° S | Cumnock, New South Wales | Reference anchor: Parkes Observatory latitude, 35 km due east of the dish. |
| UTC+11 | 163.6804° E | 19.70° S | Belep Islands, New Caledonia | |
| UTC+12 | 178.7214° E | 17.70° S | Off Ovalau, Fiji | At sea, ~1.7 km off the west coast of Ovalau. |
Questions people ask
Why does the Earth turn clockwise here?
The Earth spins west to east. Seen from above the North Pole that looks anticlockwise; seen from above the South Pole, the same spin looks clockwise. It is the same sense the Crux hand sweeps around the South Celestial Pole, because that sweep is simply the Earth turning underneath the stars.
Why are the clocks about 15.04 degrees apart instead of exactly 15?
Each clock is placed on the one meridian where the Crux hand reads exactly zero at that zone’s midnight. Neighbouring zones reach midnight one solar hour apart, but in one solar hour the sky turns 15.041 degrees, not 15, because a sidereal day is about four minutes shorter than a solar day. The extra 0.041 degrees per zone is that four minutes, shared out.
Why does the Crux hand only read zero at midnight on 31 March?
The stars run about four minutes a day ahead of the clock, so at the same clock time each night the Crux hand has moved 0.9856 degrees further round. After a year it has gone all the way round once and is back near zero. That steady creep is what turns the hand into a calendar.
Why standard time and not daylight saving?
Daylight saving is a civil rule that changes by country and by year. The sky ignores it. Each clock keeps the zone’s standard time all year, so the midnight-zero calibration never jumps.
Are the Sun and night shadow real?
Yes. The Sun’s position and the day-night line come from the same sidereal-time formula as the clocks, accurate to about a hundredth of a degree. Twilight is softened for readability, and the map is not meant for navigation.