The equatorial ring occupies a plane parallel to the celestial equator, at right angles to the meridian.

An equatorial ring was an astronomical instrument used in the Hellenistic world to determine the exact moment of the spring and autumn equinoxes.

The equatorial ring was about one to two cubits (45cm-90cm) in diameter.

The main disadvantage with the equatorial ring is that it needed to be aligned very precisely or false measurements could occur.

Above them the equatorial and polar rings whirled silently, turning as they always had.

There are even predictions that Neptune might have rings passing over its poles, in addition to the more typical equatorial rings.

However, these are only silhouettes visible against the background emission of the nebula's equatorial ring.

In its simplest form, the style is a thin slit that allows the sun's rays to fall on the hour-lines of an equatorial ring.

The time was determined by rotating the bar towards the sun so that the light shining through the hole fell on the equatorial ring.

When not in use, the equatorial and meridian rings can be folded together into a small disk.