Learner Express: Modules for Teaching and Learning
Teacher Joe Reilly asks the question, "How did our solar system form?" In 1755, a renowned German philosopher, Immanuel Kant, developed the currently-accepted "Solar Nebula" theory. He described how a solar system can develop from clouds of dust and gas that collapse into a flat spinning disk. Dr. R. Hank Donnelly, from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, describes in more detail how clouds of dust and gas produced in proto-solar nebulae coalesced under the force of gravity to form our solar system. As these materials are pulled together and become increasingly dense, they increase their spin rate—much as an ice skater pulling in her arms increases her rate of rotation, thus preserving angular momentum. The increased spinning motion counteracts part of the attraction of gravity, pulling particles outward, forming a flat disc shape. Much of the dust and small particles of rock eventually coalesced into planets. This helps explain why the planets in our solar system orbit in similar planes. Run Time: 00:02:01
High School Standard D. Origin and Evolution of Earth System: The Sun, the Earth, and the rest of the solar system were formed from a nebular cloud of dust and gas 4.6 billion years ago. The early Earth was very different from the planet we live on today.
How Planets Form
The Moon Was Formed From a Collision