Courtesy of EarthSky
A Clear Voice for Science
At one time, sailors’ livelihoods and survival depended on their lucky stars – most especially, the pointer stars of the Big Dipper. Drawing a line through the two outer stars of the bowl faithfully points to Polaris, the North Star.
Polaris is not the brightest star in the sky, as is commonly believed. It is a moderately bright second magnitude star, radiant enough to be easily seen – even on a moonlit night. Polaris, the only stable star in the northern sky, is always to your north, lighting your way to the North Pole. The direction about-face of Polaris is south, your avenue to the equator. South of the equator, Polaris drops out of the sky.
At nightfall and early evening, the seven magical stars of the Big Dipper light up your northeastern sky. The Big Dipper is not a constellation, it is an asterism, or noticeable pattern of stars. Unlike many constellations, this famous asterism looks like its namesake. It is one of several dipper patterns on the sky’s dome.
This sparkling starlit Big Dipper is so wonderfully easy to see that Chet Raymo, in his charming book 365 Starry Nights, suggested that our species is genetically predisposed to recognizing the Big Dipper. The Big Dipper is part of Ursa Major or the Big Bear constellation, making up the Bear’s tail and hindquarters.
Written by Earthsky