# Tilt Model of the Earth

1. Sep 26, 2009

### Philosophaie

Earth has a tilt to it about 23.439281° to -23.439281° from the Tropic of Cancer to the Tropic of Capricorn. The tilt faces the sun at differrent points from 23.439281° to -23.439281° creating the seasons etc. I have written a preliminary MatLab program showing the 3D Earth Equitorial Model plus some rings at the equator and at the tilt maxima and minima. What I need is some help with the trigonomic equation of the 3D loop ring that connects the two tilt maxima and minima thru the origin. Here is an example of what I have. Center loop:

x = r * cos(theta) * sin(phi)
y = r * sin(theta) * sin(phi)
z = r * cos(phi)

where r = 6378100, phi = 90 and theta = 0 - 360

#### Attached Files:

• ###### Earth3DEqualEquitorialModel.m
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Last edited: Sep 26, 2009
2. Oct 3, 2009

### Philosophaie

I have had nothing but trouble finding a set of equations to calculate the Tilt of the Earth trigonometrically for a theta (0 to 2pi) and a given Obliquity = 23.439281° (for Earth). Please disregard the MatLab program above. Any suggestions would be much appreciated.

Last edited: Oct 3, 2009