Fortune telling armillary sphere _ Fortune telling armillary sphere What does it mean?

You can see that the armillary sphere is divided into three layers from the outside to the inside. The inner two layers can rotate (note the red circle), and the innermost layer has a peephole that can move in the north-south direction. The axis of the whole armillary sphere points to the north celestial pole and is parallel to the earth's rotation axis.

When in use, aim the peeping tube at the star to be measured. The peeping tube is hollow. When aiming at the stars, you can see the stars through the holes. The innermost layer has a scale. Through the scale indicated by the peephole, the declination of the celestial body can be read, reflecting the position of the celestial body in the north-south direction.

At the same time, the second layer and the outermost layer are aligned according to certain rules (that is, when the stars are fixed, there is a simple corresponding relationship with the date), and then the innermost layer is on the penultimate layer, so that the right ascension of celestial bodies can be read on the equatorial ring and the right ascension on the ecliptic ring. These two quantities reflect the position in the east-west direction.

We can see that the armillary sphere embodies the commonly used astronomical coordinates. The outermost layer, horizon and meridian circle, is the horizon coordinate; In the middle, the celestial equator, vernal equinox and the second circle are equatorial coordinates and ecliptic coordinates.