In Britain, before the widespread use of writing, ancient people used stones to keep track of the motions of the Sun and Moon. The Polynesians learned to navigate by the stars over hundreds of kilometers of open ocean-a skill that enabled them to colonize new islands far away from where they began. The Mayan culture in Mexico and Central America developed a sophisticated calendar based on the planet Venus, and they made astronomical observations from sites dedicated to this purpose a thousand years ago. We still use some of these records in studying stars that exploded a long time ago. If you are not familiar with terms like comets and meteors, you may want to review that chapter.) Later, Chinese astronomers kept careful records of “guest stars”-those that are normally too faint to see but suddenly flare up to become visible to the unaided eye for a few weeks or months. (Many types of astronomical objects were introduced in Science and the Universe: A Brief Tour. The Chinese also recorded comets, bright meteors, and dark spots on the Sun. The Chinese also had a working calendar they determined the length of the year at about the same time as the Egyptians. They kept careful track of the rising time of the bright star Sirius in the predawn sky, which has a yearly cycle that corresponded with the flooding of the Nile River. The Egyptians of 3000 years ago, for example, adopted a calendar based on a 365-day year. Astronomy around the WorldĪncient Babylonian, Assyrian, and Egyptian astronomers knew the approximate length of the year.
However, many other ancient cultures also developed sophisticated systems for observing and interpreting the sky. Much of modern Western civilization is derived in one way or another from the ideas of the ancient Greeks and Romans, and this is true in astronomy as well. Let us now look briefly back into history. Describe Ptolemy’s geocentric system of planetary motion.Describe the motion of Earth called precession.Explain how Greek astronomers were able to calculate Earth’s size.Explain how Greek astronomers were able to deduce that Earth is spherical.Describe early examples of astronomy around the world.By the end of this section, you will be able to:
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