The Universe and our place in it STARS AND NEBULAE Edited by Nicholas Faulkner and Erik Gregersen Britannica Educational Publishing IN ASSOCIATION WITH ROSEN EDUCATIONAL SERVICES
ancient INTRODUCTION Many cultures cultures believed that the stars were lights attached to a huge dome the sky over Earth The stars maintained maintained fixed positions relative to each other as they moved across the heavens as if the sky dome were rotating around Earth Ancient people imagined patterns in the stars and grouped them into constellations representing representing various animals people mythological heroes and even everyday objects Some cultures attributed godlike powers to the stars and worshipped them Many also thought that the motions of the heavenly bodies bodies corresponded to or foretold events on Earth This belief shared by many cultures became the basis of astrology More practically the motions of the stars and planets during the year became the basis for calendars calendars which were crucial in the development of agriculture Also the stars became valuable tools for navigation especially for seafaring peoples such as the Phoenicians and Pacific Islanders 6
Approximately 100,000 stars at the core of the globular Omega Centauri cluster as captured by NASA’s Hubble Space Telescope In the last century scientists determined what stars are enormous balls of incandescent gas powered by nuclear fusion reactions in their cores However to just say that stars are balls of gas that shine through the workings of their internal energy does not do justice to their full nature and complexity Not all stars are like our Sun Some stars are massive giants doomed to burn away in merely millions of years Others will have violent and dramatic fates as supernovae white dwarfs neutron stars or even black holes 7
