Week 1: Introduction to Geography & The Earth’s Evolution
Some important terminologies to understand: Galaxy - A huge collection of gas, dust, and billions of stars and their solar systems. A galaxy is held together by gravity. Our galaxy, the Milky Way is also Akashganga. Nebula - A giant cloud of dust and gas (mostly hydrogen and helium) in space. Some nebulae can come from a dying star while others can be cause of new stars (and hence the name "star nurseries"). Star - the clump of dust and gas (nebula) gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star. Light year - a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 10 12 km Planetesimals – small celestial bodies (formed from dust, rock, and other materials) formed during the creation of planets. Theories of Origin: Most popular Modern Theory: THE BIG BANG ...