The equinoxes: 12 hours almost everywhere
Twice a year, around March 20 and September 23, Earth’s axis leans neither toward nor away from the sun. Day and night are nearly equal everywhere, from Oslo to Ushuaia.
Daylight on the March equinox
| City | Sunrise | Sunset | Daylight | Gained in a week |
|---|---|---|---|---|
| Saint Petersburg 59.94°N | 07:02 | 19:12 | 12h 10m | +38m |
| London 51.51°N | 06:05 | 18:13 | 12h 08m | +27m |
| New York 40.71°N | 07:00 | 19:08 | 12h 08m | +19m |
| Cairo 30.06°N | 06:00 | 18:07 | 12h 07m | +13m |
| Mumbai 19.07°N | 06:44 | 18:50 | 12h 06m | +7m |
| Singapore 1.29°N | 07:10 | 19:16 | 12h 07m | +1m |
| Nairobi 1.28°S | 06:38 | 18:44 | 12h 07m | ±0m |
| Lima 12.04°S | 06:13 | 18:20 | 12h 07m | −5m |
| Johannesburg 26.20°S | 06:12 | 18:20 | 12h 08m | −11m |
| Sydney 33.87°S | 06:59 | 19:09 | 12h 10m | −15m |
| Buenos Aires 34.61°S | 06:57 | 19:06 | 12h 09m | −15m |
| Wellington 41.29°S | 07:24 | 19:35 | 12h 12m | −19m |
| Ushuaia 54.81°S | 07:35 | 19:48 | 12h 13m | −32m |
Every city lands within about a quarter of an hour of 12 hours. But look at the last column: day length is changing fastest right now, in opposite directions in each hemisphere, and most quickly far from the equator.
Why it’s a little more than 12 hours
Two effects add a few minutes to every day. Sunrise and sunset are timed from the sun’s top edge, not its center, and the atmosphere bends light so the sun appears above the horizon slightly before it really is. Together they add roughly 6–14 minutes, more at higher latitudes, where the sun crosses the horizon at a shallow angle.
Equinox Mode
In the weeks around each equinox, ranking cities by day length stops working: they’re all within minutes of each other. So the daily puzzle switches to Equinox Mode 🌗 and asks which cities gained the most daylight over the past week. The table above is the cheat sheet: far north gains fast, far south loses fast, and the tropics barely move.