Sundial

Sundial

A sundial is a horological device that tells the time of day when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat plate and a gnomon, which casts a shadow onto the dial. As the Sun appears to move through the sky, the shadow aligns with different hour-lines, which are marked on the dial to indicate the time of day. The style is the time-telling edge of the gnomon, though a single point or nodus may be used. The gnomon casts a broad shadow; the shadow of the style shows the time. The gnomon may be a rod, wire, or elaborately decorated metal casting. The style must be parallel to the axis of the Earth's rotation for the sundial to be accurate throughout the year. The style's angle from horizontal is equal to the sundial's geographical latitude.

Sundial (weapon)

Sundial was the codename of one of two massive nuclear bombs planned for testing by the University of California Radiation Laboratory, Livermore Branch as part of a classified American weapons project in the early 1950s. Announced in 1954 by Hungarian–American physicist Edward Teller at a meeting of the Man Advisory Committee of the Atomic Energy Commission (AEC), it was intended to have a yield of 10 gigatons of TNT. If built and detonated, Sundial would have created a fireball up to 50 kilometers in diameter, instantly igniting everything within 400 kilometers and causing a magnitude 9 earthquake. It was thought that the explosion would lead to an apocalyptic nuclear winter.

sundial

Noun

1. A device measuring the time of day by the position of a shadow cast by a pole or plate (gnomon) upon an engraved series of marks.
2. A sea snail of the genus Heliacus.