This is a really substantial artefact with some age. Probably mid to late 1900s.
What a desk ornament to enhance your office or study this is.
If you would like to own this fantastic vintage piece of engineering, please contact me.
This impressive piece of engineering comprises of a hollow sphere mounted on an axle which allows it to be spun round. The sphere does not appear to have a join (which you would expect) showing it was not made in two pieces and then joined.
The lower (outer) rim is marked with the 12 signs of the zodiac, the 12 months of the year and the degrees 0 to 90 twice.
The upper (inner) ring is embellished with images of planets and astral bodies.