Earth-moon-sun orrery

[WhiteCube]

An equinox is coming up soon, which made me think about the earth-moon-sun system.

I'm trying to write a program that tells me where the moon is at any time.

I'd like to know the azimuth angle and altitude angle from my current position. Not an exact number, just a ballpark figure.

Roughly simulating the moon's orbit and the rotation of Earth was fairly easy. Translating position into local direction was not so simple.

What I'm stuck on is initialising the model. Knowing the date and time of the latest new moon isn't enough. It would be, if the moon was orbiting on the equatorial plane.

 

[John Joe]

Why do you want to make this system? What benefit or purpose would it serve for you? Are you planning to use it for astronomy learning, a simulation project, or something practical like navigation or stargazing?

 

[WhiteCube]

No practical reason. Its just a programming exercise.

If I really was concerned about the position of the moon, I could measure it (when visible) every day for a year.

Or, I could write a short program that uses a little bit of geometry.

While I'm writing my programs, I may get an idea about something else.

In this case, I found an interesting use for Gaussian elimination. Which I will use in other programs, that have nothing to do with orbits.