Geography : Formation of Universe | Formation of The Solar System

High School : Geography (Grade 9) Geography : Formation of Universe | Formation of The Solar System Our solar system consists of Sun + 8 Planets + 1 Dwarf planet (Pluto) + No. of Natural Satellites Pluto was demoted to dwarf planet at 26th general assembly of International Astronomical Union held at Czech republic in 2006. Only sun has its own light, which is also the nearest star to the earth Size – Wise : Jupiter - Saturn - Uranus - Neptune - Earth - Venus -Mars - Mercury Earth, Venus, Mars, Mercury --- Inner / Terrestrial Planets Jupiter, Saturn, Neptune, Uranus --- Jovian / Outer Planets Asteroids – A belt of minor planets revolving around the sun between Mars & Jupiter (Between Inner & Jovial Planets) All Planets revolve west to east around the sun except Uranus & Venus which moves east to west around the sun (Retrograde motion) No. of Satellites : Jupiter (63) - Saturn (60) - Uranus (27) - Neptune (13) - Mars (2) - Earth (1) - Venus (0) & Mercury (0) Uranus has a maximum inclination of 98* towards the sun & known as lopsided planet Earth has an inclination of 23.5* & Mercury with no inclination at all Mars is known as Red planet due to presence of Feo (Iron oxide) dust & named after roman god of war Earth is known as Blue planet due to presence of water (Approx. 71% area) Venus is the hottest planet irrespective of being 2nd in solar system due to total absence of atmosphere at Mercury Origin of Earth Gaseous Theory (1755) : By Imanuel Kant (German) Primordial matter was evenly distributed in shape of small & cold particles from which our earth & other planets of solar system formed Nebular Hypothesis (1796) : By Laplace (French) Primordial matter existed in form of intensely hot & rotating gaseous mass (Nebula), Which cooled with time, Which resulted in decrease of its volume & increase in its rotational speed, which in turn increased its centrifugal force, which when exceeded gravitational force, a ring shape deformed from nebula & many other rings formed out of its breaking. These rings on cooling became planets & satellites & remaining part of nebula is sun Planesimal Hypothesis (1900) : By Chamberlain & Moulton A wandering star approached the sun & exerted its gravitational pull on the sun, which resulted in separation of cigar shaped material from the sun. As star moved away from the sun, material separated from the sun started revolving around he sun & condensed into planets at later stage. Tidal Hypothesis : Sir James Jeans (British) +Harold Jeffrey Sun was a gaseous mass, another star several times larger than sun accidentally came close to it & pulled gaseous mass away from the sun due to its gravitational pull. Giant tongue of matter came out from the sun & planets were formed Big Bang Theory (1929) : Edwin Hubble (American) Everything in the world emerged from a point known as singularity (of indefinite mass & indefinite density) about 13.7 billion years ago. As galaxies moved away, space between them expanded ( Red shift). As the universe expanded, hot radiation in original firewall cooled down, which led to formation of different galaxies which further broke into stars & finally stars broke to form planets. (0:10 - 10:55) Ancient people believed that the Earth was the center of the earth with just the Sun, Moon a few planets and some stars. Galileo was the first to explain in the 17th century, that the earth was not the center of the universe, as was believed by the ancient people. Even as early as the beginning of the 20th century some scientists thought that the universe was no larger than the milky way galaxy. Most Scientists believe that the Universe began with the Big Bang around 13.7 billion years ago. Our Solar system is believed to have formed 4.7 billion years ago explained by the Solar Nebular Theory. Click on the Link for online Video for Geography : https://youtu.be/NLYX1EYct5w Video by Edupedia World (www.edupediaworld.com), Online Education, All Right Reserved.