Hand Measures

The Big Dipper shifts orientation during the year, left, from close to the northern horizon in autumn to nearly overhead in spring. These major seasonal changes are due to Earth's annual orbit around the sun, above left, which points us toward different quadrants of the cosmos as the seasons pass. This action causes many star groups to be well seen only during one season, but the Dipper's northerly location keeps it pivoting the celestial pole and in view all year. As explained in the text, sky distances in degrees can be roughly measured using your hand held at arm's length, above.