Aurinkokelloilla

Aurinkokelloilla is the Finnish word for sundials. A sundial is an instrument that tells the time of day by the position of the Sun. Sundials typically consist of a gnomon, which casts a shadow, and a surface marked with lines indicating the hours. As the Sun moves across the sky, the shadow cast by the gnomon moves, indicating the time.

There are several types of sundials. The most common type is the horizontal sundial, where the dial plate is horizontal. A vertical sundial is mounted on a vertical surface, such as a wall. An equatorial sundial has its dial plate parallel to the Earth's equator. Armillary sundials are spherical and consist of a series of rings that represent circles of the celestial sphere.

Sundials were the primary timekeeping devices for centuries, dating back to ancient civilizations such as the Egyptians and Babylonians. Their accuracy depends on the latitude and the alignment of the gnomon. Sundials were gradually replaced by mechanical clocks, which offered more consistent timekeeping, especially in cloudy weather or at night.

Today, sundials are mostly decorative or educational objects. They can be found in gardens, parks, and historical sites. Studying sundials provides insight into the history of astronomy and timekeeping. The design and construction of sundials require an understanding of geometry and celestial mechanics.