9781422283356

WORDS TO UNDERSTAND

celestial spheres —crystal spheres upon which the planets and stars were thought to move by the Ancient Greeks. There are no spheres, but astronomers today sometimes use the idea of a celestial sphere to describe the positions of objects in space in relation to the Earth.

epicycle —a small circle, the center of which rolls around a larger circle.

fundamental essence —an idea put forward by the Greek philosopher Anaximander. This was the mysterious substance from which all other materials in the Universe came. meteor —a streak of light in the night sky caused by a rocky particle from space glowing white hot through friction as it enters the Earth’s atmosphere. A meteor big enough to pass through the atmosphere and strike the surface is called a meteorite.

RESEARCH PROJECT

Using the Internet or your school library as a guide, create a model of the “celestial spheres” proposed by Ptolemy. Include the ecliptic path, or route that the Sun follows through the sky from Earth’s perspective.

TEXT-DEPENDENT QUESTIONS

1. What did the ancient Egyptians believe about the Sun? 2. What was Ptolemy’s concept of the Universe?

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