SCMA 1290 Lecture Notes - Lecture 2: Geocentric Model, Copernican Revolution, Ellipse
Document Summary
A large cloud of gas and dust is called a solar nebula, or simply a nebula. Planetesimals are made of rock, dust and ice. They form the outer part of the disk which were building blocks for planets while the centre of the disk created the sun. About five billion years ago, a giant cloud of gas and dust collapsed to form our solar system. A solar nebula is a large cloud of gas and dust in space. A solar nebula was the beginning of our solar system. Gas a dust gathered together in the outer parts of the disk to form planetesimals (asteroid like objects). In a geocentric system, earth is at the center of revolving planets and stars. Greek astronomer ptolemy further developed the geocentric model. Greeks, ptolemy thought that earth is at the center of a system of planets and stars. Ptolemy"s model was incorrect, it still explained the motions observed in the sky fairly accurately.
