MPPSCADDA 1 GEOGRAPHY OF WORLD AND INDIA CONTENT WORLD GEOGRAPHY ❖ ❖ ❖ ❖ ❖ ❖ ❖ ❖ ❖ INDIAN GEOGRAPHY ❖ ❖ ❖ ❖ ❖ ❖ 2 MPPSCADDA 3 GEOGRAPHY WORLD 1. UNIVERSE INTRODUCTION TO GEOGRAPHY • The word ‘Geography’ is a combination of two Greek words "geo" means Earth and "graphy" means write about. • Geography as a subject not only deals with the features and patterns of surface of Earth, it also tries to scientifically explain the inter-relationship between man and nature. • In the second century, Greek scholar Eratosthenes (Father of Geography) adopted the term 'Geography'. BRANCHES OF GEOGRAPHY Physical Geography Human Geography Bio - Geography Cultural Geography Climatology Economic Geography Geomorphology Historical Geography Glaciology Political Geography Oceanography Population Geography Biogeography Social Geography Pedology Settlement Geography PHYSICAL GEOGRAPHY It deals with the physical environment and various processes that bring about changes in the physical environment on the Earth's surface. It includes: 1. Bio-Geography: The study of the geographic distribution of organisms. 2. Climatology: The study of climate or weather conditions averaged over a period of time. 3. Geomorphology or Physiographic: The scientific study of landforms and processes that shape them. 4. Glaciology: The study of glaciers and ice sheets. 5. Oceanography: The study of all aspects of the ocean including temperature, ocean current, salinity, fauna and flora, etc. 6. Pedology: The study of various types of Soils. 4 HUMAN GEOGRAPHY Human geography deals with the perspective of human and its functions as well as its interaction with the environment. It studies people, communities and cultures with an emphasis on relations of land across space. It includes: 1. Cultural Geography: The study of the spatial variations among cultural groups and spatial functioning of the society. 2. Economic Geography : It studies the distribution and utilization of resources of the Earth. 3. Historical Geography: The study of the past like the reconstruction of past environment and the study of sequences of changes with the passage of time at a place. 4. Political Geography: It is the study of the political phenomenon like national interests, nations and international relations. 5. Population Geography: The study of the characteristics of people living in an area such as sex-ratio, literacy, migration, etc. 6. Social Geography: The study of the spatial arrangement of social phenomena like caste, religion, racial groups and their social implications. 7. Settlement Geography: It deals with the: nature of human shelter. UNIVERSE • Universe is the whole of existence, including planets, stars, galaxies, the contents of intergalactic space, all matter and energy. The size of the universe is unknown and infinite. • The study of universe is called as Cosmology. The age of universe is approximately 13.8 million years (13.8 x 109years). COMPOSITION OF UNIVERSE • The Universe is believed to be composed of dark energy, dark matter, hydrogen and helium. THEORIES of Evolution of the Universe • Aristotle propounded geocentric theory where the Earth was the centre of the universe and the sun, the moon and the other planets are orbiting the Earth. • In 140 AD, Claudius Ptolemy propounded the theory that the Earth was the centre of the universe and the sun and other heavenly bodies revolved around it. • In 1543, Nicholas Copernicus argued that the sun, and not the Earth, was the centre of the universe. Johannes Kepler supported Copernicus but said that the sun was the centre of the solar system and not the universe. • In 1805, Hershel made it clear that the solar system was a part of the much larger system of stars called galaxy. 5 The three main theories put forward to explain the origin and evolution of the universe are: The Big Bang Theory • The 'Big Bang theory' is related to the origin of the Universe, Milky Way and Solar system. • It explains the origin of the universe from the earliest known period through its subsequent large- scale evolution. • The measurement of the expansion rate of the universe places this moment approximately 13.7 billion years ago, which is thus considered the age of the universe. • This theory was propounded by Georges Lemaitre and George Gamow in 1894-96. Later in 1967, Robert Wagner explained this theory. • According to this theory, whole universe was concentrated on a hot and dense point some 13.7 bn years ago. Due to high concentration, there was a sudden explosion which was termed as Big-Bang. • Due to primordial explosion, the matter was broken into pieces, which were thrown out with high speed in all directions forming stars and galaxies which are still moving away from one another. Pulsating (Oscillating) Universe Theory • It states that universe periodically expands from the explosion of the primordial body, then contracts back and explodes again, over immensely long cycles, ad infinitum. At present, the universe is expanding. Steady State Theory • This Theory was developed in 1948 by Fred Hoyle, Thomas Gold and Hermann Bondi. It states that the universe is always expanding though it maintains a constant average density. GALAXY • A galaxy is a huge congregation of stars held together by the forces of gravity. • Infinite group of these swirling galaxies are visible to us collectively in the form of Universe. • Every Galaxy is estimated to contain 100 billion stars. • Milky Way: Our galaxy is Milky Way Galaxy (or the Akash Ganga) which contains our Solar System. • It is spiral in shape. It consists of over a 100 billion stars rotating and revolving about its centre. The nearest spiral galaxy to ours is Andromeda. • In 1924, Edwin Hubble first demonstrated existence of galaxies beyond Milky Way. • There are three main types of galaxies: 1. Elliptical Galaxies shaped like a "Spheriod" or "Elongated Sphere"; 2. Spiral Galaxies have three main components and 3. Irregular Galaxies have no regular or symmetrical structure. • Spitzer space telescope in 2005, produced clear proof that the shape of our Milky Way is Barred spiral. 6 STAR • Stars are self-luminous and heavenly bodies that are extremely hot and have own light. Star forming matter is richer in hydrogen and helium. • A star's color indicates the temperature of its surface. Blue color denotes maximum temperature. • The nearest star to Earth is the Sun. The oldest star HE 1523-0901, is an estimated 13.2 billion years old. The most massive star known is "Eta Carinae" having with 100-150 times as much mass as the Sun. • "VY Canis Majoris" is one of the largest known stars by radius and the most luminous. • The smallest star in the universe is a Red Dwarf known as "Gilese 623b". Its mass is one tenth the mass of the sun. STAGES OF STAR • Universe is a group of infinite galaxies and each galaxy contains billions of stars. Stars are the most fundamental building blocks of galaxies. Whole lifecycle of stars is divided into 5 stages: 1. Stage 1 : These stars are formed by nebulae having ingredient Hydrogen and Helium present in galaxies. These are born within the clouds of dust scattered throughout most galaxies. During the first life-cycle phase of a high-mass star, the hydrogen in the core burns until only helium is left. 2. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can bring to collapse under its own gravitational attraction. In the initial stage of their development, stars are known as Protostar. Subsequently, a star enters the next phase of development which describes the stars as 'main sequence star'. The stages a star will go through and how long it will last in each stage depends on the mass. Heavy stars evolve quicker than light stars. Heavy stars live shorter lives than the common stars because even though they have a larger amount of hydrogen for nuclear reactions, their rate of consuming their fuel is much greater. 3. Once a star has burnt through all its fuel i.e. hydrogen fuel in its' core, nuclear reactions can no longer continue. So, the core begin to contract within it's own gravity. This brings additional hydrogen into a zone where temperature and pressure are adequate to cause fusion to resume in a shell around the core. In this stage a star is termed as 'Red Giant'. 4. In the Second (maturing) process, a star takes millions of year from the beginning of the collapse to adulthood. A star of the size of our Sun requires about 50 million years to mature and will stay in this mature phase for approximately 10 billion years. The smallest stars, known as red dwarfs, may contain as little as 10% the mass of the Sun, while the most massive stars, known as hypergiants may be 100 or more times more massive than the Sun. In the stage of red giant or hyper giant a burst of nuclear fusion occurs by which dwarf may become Nova or Super Nova. 7 5. After this the stars, according to their size reaches to one of the three stages: Black dwarf, Neutron star or Black hole, of death. o Small stars like Sun — If after Novae explosion the remaining Mass is within 1.44 times of solar masses, the star will become white dwarf and shall reach to death in the form Black dwarf. A solar mass is the standard way to describe mass in astronomy (One solar mass is equal to the mass of the Sun, or about 1.98892 ×10^30 kg) o Stars of Medium size—If after Supernovae explosion the remaining mass of star is within the limit of 1.44 times to 3 times of solar masses it will become Neutron star. o Stars of Large size — If after Supernovae explosion the remaining mass is more than 3 times of the Solar masses, star will become Black Hole.