The Ptolemaic system of the universe with the spherical Earth in the center. Complete with the crystal sphere, blinking stars, the day-night Earth cycle and axis tilt.

Video demo here, here, here and here!

Two versions: 

1. THE VERTICAL DOME

Illustrating the rotation of the system from a top view. The spheres are cyclically shifting up and down, illustrating the orbital tilt. Animated in Geometry Nodes.

2. THE ROTATING SPHERES

The spheres are rotating in multiple axis, emphasizing the "orb-nature" of the universal structure.

Enjoy ! Happy Blending !

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NOTE - The Ptolemaic model has specific orbital cycle parameters and epicycles defined. This animation is true to the spirit and overall dynamics of the model, but, as one of the reviews pointed out,  it is not following those parameters exactly - simply because it concentrates on the aesthetics. (You can, of course, modify the setup to the parameters you wish, set up the adjustable speeds of the planet rotations to match the model - or any model you can come up with, in fact.)

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NOTE

-(Since it is a concept demonstration, it is kept as simple as possible.) The GeoNodes trees are kept clean for easier readability and have detailed explanations. Everything is built from the base. The point of these setups is to provide a base core of the concept, node from node, instead of contracting all into node groups with exposed settings, which makes everything harder to read and dissect.

You can embellish, refine as you wish based on the core or realize your own ideas.

-Read the text description, it has a lot of useful info !

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Recomended blends -

The Visitor

Kinetica

The Surface Voronizer