ABSTRACT
This chapter contains a map of Ursa Major, the third largest of all the constellations; it covers 1,280 square degrees, and is exceeded only by Hydra (1,303) and Virgo (1,294). The seven leading stars of Ursa Major make up the pattern known variously as the Plough, King Charles’ Wain and (in America) the Big Dipper. Merak and Dubhe are known as the Pointers, because they show the way to the Pole Star. The most celebrated star in Ursa Major is Zeta (Mizar). On any clear night its companion, 80 Ursae Majoris or Alcor is clearly visible without optical aid, the classic example of a naked-eye pair. The semi-regular variable Z Ursae Majoris lies in the “bowl”, not far from Delta. Its range is between magnitude 6.8 and 9.1, and there is a rough period of around 196 days. Since it never becomes really faint, and is easy to find, it is a favourite “training” object for new variable-star observers.
