The Ring Sundial

Englische Version des Artikels "Die Ring-Sonnenuhr" 216.RSU

It is also called the queen of sundials.

Time to bring with you

Long before the wristwatches of today existed, people already appreciated portable timepieces. For this purpose, they used a ring-shaped sundial that they wore on a necklace. The ring sundial from AstroMedia is perhaps a little too big for this, but nevertheless a real piece of jewellery. It shows its user the true solar time at any place on earth, as long as you know the latitude of the place as well as the month and day. Most importantly, unlike most other sundials, you don't need to know where the celestial directions are: The ring sundial will north itself, provided you know whether it is just before or after the sun's noon Position.

The parts of the ring sundial

The rotating suspension shows with its reading mark the position of the zenith, which is vertically above the observer. The opposite lowest point on the half of the celestial sphere that is invisible to us is called the nadir.
The meridian ring indicates the position of the so-called noon line, where the sun is at its highest point. The hour ring shows the position of the celestial equator, in the middle of which lie the north and south celestial poles. Both ends of the sun position scale point in the same direction. The sliding pinhole in the sun position scale projects a tiny image of the sun onto the inner edge of the hour ring, where the time is read. Its position on the scale indicates the Sun's declinations, which vary according to the season.