The Mystery of Our Daylight Curve

This is the story of how the four fixed points of the solar year, the spring and autumn (fall) equinoxes and the two solstices, summer and winter, can be observed without looking at the calendar.

Greenwichmeantime.com has a Time Zone portal, with some really useful features like a fast-track converter for time in a chosen place and GMT.

It also has a map of the world with a “live” daylight curve, which is moving across continents and time zones in synch with the way the Earth is going through the real daytime and nighttime cycle.

Visualisations are great and make physical phenomena much more comprehensible. There is a problem though. The deluge of words and images we consume has been growing at such a fast rate that it is very easy to gloss over anything and stop noticing changes.

This is what happened with the Daylight Curve. It was there, as a curve and suddenly, on Equinox Day, it presented itself as an almost straight line. Weird? Not at all, the curve itself changes shape as the seasons go by, to reflect the change in Earth’s position relative to the Sun.

Does this mean that what happens at the Equinox can be seen on the map? Yes it does, was the answer, as both hemispheres, the Northern and the Southern one, get an (approximately) equal share of light and darkness, and at the same time.

One point of synchronicity, happening twice a year, that makes the Daylight Curve the simplest calendar ever. Do you agree?