Star clock

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

A star clock (or nocturnal) is a method of using the stars to determine the time. This is accomplished by measuring the Big Dipper's position in the sky based on a standard clock, and then employing simple addition and subtraction; this method requires no tools; others use an astrolabe and a planisphere.

A clock's regulator can be adjusted so that it keeps the Mean Sidereal Time rate; when it is then set to an observer's Local Mean Sidereal Time then a star will transit the meridian (passing directly north or south) at the sidereal time of the star's Right Ascension.

See also[edit]

External links[edit]