Venus is considered as 'Earth's-twin' because its size and shape are very much similar to that of the earth. Crust: This is the outermost layer of the earth. In ancient times, people used to determine directions during the night with the help stars. However, scientists in later period took up the problems of origin of universe rather than that of just the earth or the planets. Two points on the globe through which the needle passes are two poles - North Pole and South Pole. At a later date, the arguments considered of a companion to the sun to have been coexisting. For example, in Russia, there are as many as eleven standard times. It is because here the sun does not rise much above the horizon. 3 sec, OTP has been sent to your mobile number and is valid for one hour. Similarly, the distance between the galaxies is also found to be increasing and thereby, the universe is considered to be expanding. A volcano is an opening in the earth’s crust through which gases, molten rocks materials (lava), ash, steam etc. Notification | As the earth cooled, the water vapour released started getting condensed. Tropic of Capricorn \[(23{{{}^{1}/{}_{2}}^{o}}S)\] in the Southern Hemisphere. The solar winds were not all that intense to cause similar removal of gases from the Jovian planets. This later led to the development of the outer surface in the form of a crust. Its value is 0° longitude and from it we count 180° eastward as well as 180° westward. This theory explains what exactly happened at the very beginning of time to our universe. The crust of the Earth has two distinct types: continental crust and oceanic crust. It is thicker at continents (30 - 40 km) and its thickness underneath the ocean basin varies from 5-10 kms. This is far from the present day picture of the earth. These initial density differences gave rise to differences in gravitational forces and it caused the matter to get drawn together. Amazing Facts Evolution of the Earth. The universe became transparent. Understanding the basic structure of earth is very important to learn higher concepts well. Light travels at a speed of 300,000 km/second. The study of landforms, their processes, form, and sediments at the surface of the Earth (and sometimes on other planets) is known as Geomorphology. Origin of earth is matter of great speculation and discussion. The present composition of the earth’s atmosphere is chiefly contributed by nitrogen and oxygen. Therefore, if rays are always slanting and provide less heat. Lithosphere: The firm outer part of the earth, comprising of the crust and upper mantle. Category : UPSC Early Theories of the Origin of the Earth . 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. A large number of hypotheses were put forth by different philosophers and scientists regarding the origin of the earth. During the cooling of the earth, gases and water vapour were released from the interior solid earth. The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids form the solar system. These small-rounded objects by the process of cohesion develop into what is called planetesimals. There are three stages in the evolution of the present atmosphere. The planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium. NCERT Notes Origin And Evolution Earth Part2 NCERT Notes: The Origin And The Evolution Of The Earth [Geography Notes For UPSC] NCERT notes on important topics for the IAS aspirants. | This allowed heavier materials (like iron) to sink towards the centre of the earth and the lighter ones to move towards the surface. | Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. This started the evolution of the present atmosphere. The sun is the ultimate source of heat and light for the solar system. These clumps continue to grow into even denser gaseous bodies, giving rise to formation of stars. Earth formed around 4.54 billion years ago by accretion from the solar nebula. The crust is the outermost layer of the earth. It is brittle in nature. This line is known as the equator. One of the earlier and popular arguments was by German philosopher Immanuel Kant. The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion. Considering this, the distances the light will travel in one year is taken to be one light year. Free Videos, Contact Us As time passes, galaxies move further and further apart. It is about 2,900 kilometers thick and makes up 84% of Earth’s total volume. However, the present scientists do not accept either of the explanations. The earth has a layered structure. Notes We often call it a solar family, with the sun as its Head. Its depth varies from 16 km – 40 km. They are semi-circles and the distance between them decreases steadily polewards untill it becomes zero at the poles, where all the meridians meet. The following are considered to be the stages in the development of planets : The stars are localised lumps of gas within a nebula. India located east of Greenwich at 82°30'E in 5 hours and 30 minutes ahead of GMT. Mercury, Venus, Earth, Mars, Jupiter, Uranus, Saturn and Neptune. Why Studyadda? The lithosphere is the rigid outer part of the earth with thickness varying between 10 … Under such conditions, most of our knowledge about the interior of the earth is largely based on analogies and inferences. Modem scientists refer to the origin of life as a kind of chemical reaction, which first generated complex organic molecules and assembled them. The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. Eventually, growing nebula develops localised clumps of gas. Unlike parallels of latitude, all meridians are of equal length. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere. Jobs It is carried by a rocket and placed in the orbit around the earth. There are eight planets in our solar system. Mathematician Laplace revised it in 1796. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geological change and biological evolution.. Thereafter, the expansion has slowed down. Each zone thus covers 15° of longitude. The early terrestrial crust appeared approximately 4.5 billion years ago, after the late stages of planetary accretion. Methane, carbondioxide and ammonia released from molten mass covered the surface. Origin of Earth and Evoluation of the Environment Fig. What should you understand about the interior of the earth? The earth's oceans were formed within 500 million years from the formation of the earth. Mercury is nearest to the sun. Test Series These bodies are called asteroids. The diameters of individual galaxies range from 80,000-1,50,000 light years. | 2.1 Theories about the formation of the crust Arctic Circle of \[66{{{}^{1}/{}_{2}}^{o}}\] north of the equator. Due to gradual increase in density the temperature inside has increased. Edwin Hubble, in 1920, provided evidence that the universe is expanding. The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. From the outermost end of the atmosphere to the centre of the earth, the material that exists is not uniform. In 1920, Edwin Hubble, the man after whom the famous Hubble space telescope is named, he provided evidence that the universe is expanding and as time passes, galaxies move further and further apart. Ncert Solutions Geoid means an earth-like shape. The ozone layer was formed. The first stage is marked by the loss of primordial atmosphere. In 1838, Sir George Darwin suggested that initially, the earth and the moon formed a single rapidly rotating body. geography optional (geomorphology) by shamim anwer this notes are by keynote ias. The whole mass became a dumb-bell-shaped body and eventually it broke. Privacy Policy | It can be assumed mat life began to evolve sometime 3.800 million years ago. With passage of time it cooled further and solidified and condensed into a smaller size. In this article (geography section), we discuss the interior of the earth. Origin and evolution of Universe, Solar system Geological History of the Earth Geological Time scale Latitude and Longitude including important Parallels and Meridians Motions of the Earth and their effects Inclination of the Earth’s Axis and its effects Local and Standard Time and the International Date Line, Calendar The equator represents the zero degree latitude. . layer of gases encircling a planet that is seized in place by the gravity of that body. Each degree is further divided into minutes, and minutes into seconds. A light year is a measure of distance and not of time. All the eight planets of the solar system move around the sun in fixed paths. This article talks about the Geography as an assimilating discipline as a science of spatial characteristics and Divisions of geography and significance of physical geography. Some of the Indian satellites in space are INSAT, IRS, EDUSAT, etc. It moves around its axis, which is an imaginary line. While watching the night sky, you may notice various patterns formed by different groups of stars. The moon is the only natural satellite of the earth. ... NCERT Textbook - The Origin and Evolution of the Earth; Test: The Origin And … Our earth, however , is part of a vast universe. The Origin and Evolution of the Earth class 11 Notes Geography in PDF are available for free download in myCBSEguide mobile app. Lithosphere, Atmosphere, and Hydrosphere of the Earth. The UV rays from the sun brokeup water into Hydrogen and Oxygen and the lighter H2 escaped. Into even denser gaseous bodies, giving rise to differences in gravitational forces it! 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