stayradiated / solar-clock

I'm having a hard time trying to figure out what time it is.

Solar Clock

Why?

I want to understand how we calculate time.

From what I understand it's based on the movement of the Earth around our Sun.

We have exactly 24 hours in our day -- but this is "Mean Solar Time" -- the average length of a day.

I want to know what the actual length of the day is.

Inspiration

Earth and Sun by Bartosz Ciechanowski is a work of art.

I've been reading through the source code trying to understand all the calculations and numbers that are used. There are a lot.

1. Ellipses

I've started by plotting the orbit of the Earth around our Sun.

The Earth does not orbit in a perfect circle. It looks like a circle, but it's actually an Ellipse.

e² = 1 - y² / x²

http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Beth_Caissie/eccentricity.htm

The eccentricity of the Earth changes over time due to gravitational forces from other planets in the Solar System (mostly Jupiter).

It ranges from almost a perfect circle (0.0034) to quite elliptical (0.058).

The eccentricity of the Earth's orbit is currently around 0.0167.

This is a small diagram to help visualize those numbers:

                   0.0167
|------------------*-----------------------------------------------------------|
0.0034                                                                     0.058