Aurinkokello

Aurinkokello is the Finnish word for sundial. A sundial is a device that tells the time of day by the apparent position of the Sun. It consists of a gnomon, which casts a shadow onto a surface marked with lines indicating the hour. As the Earth rotates, the Sun appears to move across the sky, and the shadow cast by the gnomon shifts accordingly, pointing to different hour markers on the sundial.

There are several types of sundials, including horizontal, vertical, and equatorial sundials. Horizontal sundials are placed on a flat, horizontal surface. Vertical sundials are mounted on a vertical wall, and equatorial sundials are designed to be parallel to the Earth's equator. The accuracy of a sundial depends on its design, its geographical location, and the alignment of its gnomon. Sundials do not function at night or on heavily overcast days when the Sun is not visible.

Historically, sundials were the primary timekeeping devices for centuries before the invention of mechanical clocks. They were used in ancient civilizations such as Egypt, Greece, and Rome. While largely replaced by modern timekeeping technologies, sundials remain popular as decorative garden ornaments and educational tools, demonstrating the principles of celestial mechanics and the passage of time. The study and creation of sundials is known as gnomonics.