Media Ncert Solutions This led to a huge expansion. As a result the material inside started getting separated depending on their densities. Some countries have a great longitudinal extent and so they have adopted more than one standard time. The distribution of matter and energy was not even in the early universe. During the cooling of the earth, gases and water vapour were released from the interior solid earth. NCERT notes on important topics for the IAS aspirants. Geography is an English word It has its origin m Greek, which relates to the description of the earth. The Big Bang Theory considers the following stages in the development of the universe. Life was confined to the oceans for a long time. Cooling of the earth also condensed water vapour into liquid water filling the depressions to form seas. The thickness and density of the crust vary under the oceanic and continental areas. Our earth has only one satellite, that is, the moon. It is now generally believed that the formation of moon, as a satellite of the earth, is an outcome of 'giant impact' or what is described as "the big splat". The North star indicates the north direction. The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion. They are semi-circles and the distance between them decreases steadily polewards untill it becomes zero at the poles, where all the meridians meet. ... NCERT Textbook - The Origin and Evolution of the Earth; Test: The Origin And … Light travels at a speed of 300,000 km/second. Geoid means an earth-like shape. The formation of stars is believed to have taken place some 5-6 billion years ago. As it grew, some energy was converted into matter. These are optional notes but very relevant for GS-1 Geography as well. Under such conditions, most of our knowledge about the interior of the earth is largely based on analogies and inferences. The earth's oceans were formed within 500 million years from the formation of the earth. Yet, a part of the information is obtained through direct observations and analysis of materials. The crust of the Earth has two distinct types: continental crust and oceanic crust. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. Oxygen combined with ammonia and methane to form water, CO2 and others. Mercury is nearest to the sun. Based on all the evidences from Seismic data and their analysis, the earth’s interior has been divided into three layers. The expansion of universe means increase in space between the galaxies. Apart from the stars, planets and satellites, there are numerous tiny bodies which also move around the sun. The age of Earth is approximately one-third of the age of the universe. The planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium. The inner planets are Mercury, Venus, Earth, and Mars. | Lithosphere: The firm outer part of the earth, comprising of the crust and upper mantle. Venus is considered as 'Earth's-twin' because its size and shape are very much similar to that of the earth. The Origin and Evolution of the Earth class 11 Notes Geography in PDF are available for free download in myCBSEguide mobile app. The age of Earth is approximately one-third of the age of the universe. The sun is about 150 million km away from the earth. Study Packages It provides the pulling force that binds the solar system. The best app for CBSE students now provides The Origin and Evolution of the Earth class 11 Notes Geography latest chapter wise notes for quick preparation of CBSE exams and school-based annual examinations. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more condensation and more rains. Why Studyadda? The gravitational force within the lumps leads to the formation of a core to the gas cloud and a huge rotating disc of gas and dust develops around the gas core. | A light-year is a measure of distance and not of time. Larger bodies start forming by collision, and gravitational attraction causes the material to stick together. | Your email address will not be published. This equals to 9.4611012 km. Within first three minutes from the Big Bang event, the first atom began to form. It is also called the Pole Star. Origin and Evolution of Earth ... Velocity tends to increase with depth and ranges from approximately 2 to 8 km/s in the Earth's crust, up to 13 km/s in the deep mantle. Tropic of Capricorn \[(23{{{}^{1}/{}_{2}}^{o}}S)\] in the Southern Hemisphere. Thereafter, the expansion has slowed down. | From me surface to deeper depths, the earth's interior has different zones and each of these contains materials with different characteristics. FAQ For example, in Russia, there are as many as eleven standard times. This area, therefore, receives the maximum heat and is called the Torrid Zone. Such vents or openings occur in those parts of the earth’s crust where the rock strata are relatively weak. The word astheno means weak. 2. Till recently (August, 2006), Pluto was also considered a planet. The crust is the outermost layer of the earth. | ... Impact of Pleistocene Ice age on the crust of the Earth. These notes will also be useful for other competitive exams like banking PO, SSC, state civil services exams and so on. Oceans began to have the contribution of oxygen through the process of photosynthesis. Similarly all paralles south of the equator are called 'south latitudes.'. 1.2: Formation of planets The crust of the earth was formed from cooling and hardening of the molten matter and hot gases. It blasted a large part of the earth into space. NCERT Extracts - The Origin and Evolution of the Earth . Category : UPSC Early Theories of the Origin of the Earth . This happened not only in case of the earth, but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds. Its diametre is only one-quarter that of the earth. Edwin Hubble, in 1920, provided evidence that the universe is expanding. At the Big Bang the “tiny ball” exploded violently. This started the evolution of the present atmosphere. A galaxy contains a large number of stars. The process through which the gases were outpoured from the interior is called degassing. It is carried by a rocket and placed in the orbit around the earth. The real earth ha no such needle. Origin and Evolution of Earth and Related theories. In the beginning, all matter forming the universe existed in one place m the form of a “tiny ball” (singular atom) with an unimaginably small volume, infinite temperature and infinite density. This tells us that the oceans are as old as 4,000 million years. Our solar system consists of the sun (the star), 8 planets, 63 moons, millions of smaller bodies like asteroids and comets and huge quantity of dust-grains and gases. Test Series Reaching the centre of the earth and make observations or collect samples of the materials is almost impossible. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere. A light year is a measure of distance and not of time. Earth formed around 4.54 billion years ago by accretion from the solar nebula. The terrestrial planets are smaller and their lower gravity could not hold the escaping gases. The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. The equator represents the zero degree latitude. The sun is the ultimate source of heat and light for the solar system. Lalit Sardana Sir Both Planetesimal and tidal hypothesis came under the category of catastrophic theories, Planetesimal Hypothesis: It was given by two American scientists, Chamberlin and Moulton (1900), to overcame the objections raised against Nebular Hypothesis ... mantle layer below. The geological time scale (GTS), as defined by international convention, depicts the large spans of time from the beginning of the … This is far from the present day picture of the earth. It always remains in the same position in the sky. The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. The first stage is marked by the loss of primordial atmosphere. This line is known as the equator. These are, therefore, called Frigid Zones (very cold). Another imaginary line running on the globe divides it into two equal parts. Therefore, if rays are always slanting and provide less heat. Questions Bank The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids form the solar system. The local time at this meridian is taken as the standard time for the whole country. Hydrogen and helium were the gases which intially formed the earth's atmosphere. This assemblage was such that they could duplicate themselves converting inanimate matter into living substance.

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