Types of Mineral

Day 23 ...................................75-79 CONTENT Physiography of India Day 24 ...................................80-88 Drainage System of India Day 16 .....................................5-11 Universe Day 25 .................................89-102 Day 17 ...................................12-23 Climate of India Rocks and Minerals Day 26 ...............................103-115 Day 18 ...................................24-34 Maps of India and World Concepts of Geomorphology Day 27 ...............................116-141 Day 19 ...................................35-44 Agriculture Landforms and its Evolution Day 28 ...............................142-161 Day 20 ...................................45-54 Climatology Mineral Resources Day 21 ...................................55-63 Day 29 ...............................162-174 Atmospheric Circulation & Weather Transport Systems Day 22 ...................................64-74 Day 30 ...............................175-184 Oceanography Migration TARGET PT 2020 5 DAY - 16 UNIVERSE Theories on origin of the Universe Nebular Hypothesis: (Initial arguments were given by German philosopher Immanuel Kant Mathematician Laplace revised it in 1796). The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. Planetesmial Hypothesis: In 1900, Chamberlain and Moulton considered that a wandering star approached the sun. Sir James Jeans and later Sir Harold Jeffrey supported the argument. At a later date, the arguments considered of a companion to the sun to have been coexisting. These arguments are called binary theories. In 1950, Otto Schmidt in Russia and Carl Weizascar in Germany somewhat revised the ‘nebular hypothesis’. Big Bang Theory/ Expanding Universe Hypothesis: It was given by Edwin Hubble. According to “Big Bang Theory” everything in the universe emerged from a point known as ‘Singularity’ 15 billion years ago. Later on, this point expanded and inside it galaxies move apart due to which empty space between them expanded. All matter in the universe was created at one instant in fi xed moment of time. A single fi re ball existed along with wispy clouds of matter. When it exploded, it formed cluster of galaxies which exploded to form stars and then stars exploded to form planets. Solar System 6 TARGET PT 2020 The solar system comprises the Sun and its eight planets which are believed to have been developed from the condensation of gases and other lesser bodies. All the planets revolve round the Sun in elliptical orbits. Alternatively, the fi rst four are called Terrestrial, meaning earth-like as they are made up of rock and metals, and have relatively high densities. The rest four are called Jovian or Gas Giant planets. Jovian means Jupiter-like. Most of them are much larger than the terrestrial planets and have thick atmosphere, mostly of helium and hydrogen. Till recently (August 2006), Pluto was also considered a planet. However, in a meeting of the International Astronomical Union, a decision was taken that Pluto like other celestial objects (2003 UB313) discovered in recent past may be called ‘dwarf planet’. The eight bodies offi cially categorized as planets are often further classifi ed in several ways: By composition: ! Terrestrial or rocky planets: Mercury, Venus, Earth, and Mars. ! The terrestrial planets are composed primarily of rock and metal and have relatively high densities, slow rotation, solid surfaces, no rings and few satellites. ! Jovian or gas planets : Jupiter, Saturn, Uranus, and Neptune: ! The gas planets are composed primarily of hydrogen and helium and generally have low densities, rapid rotation, deep atmospheres and lots of satellites. By size: ! Small planets: Mercury, Venus, Earth, Mars. (The small planets have diameters less than 13000 km.) ! Giant planets: Jupiter, Saturn, Uranus and Neptune. (The giant planets have diameters greater than 48000 km.The giant planets are sometimes also referred to as gas giants.) By position relative to the Sun: ! Inner planets: Mercury, Venus, Earth and Mars. ! Outer planets: Jupiter, Saturn, Uranus, Neptune. The asteroid belt between Mars and Jupiter forms the boundary between the inner solar system and the outer solar system. Kuiper Belt: The Kuiper Belt (sometimes referred to as the Kuiper-Edgeworth Belt) is an area of the outer solar system that is estimated to stretch across 20 astronomical units (AU) of space. It contains small solar system bodies made mostly of ices. The ices are frozen volatiles (gases) such as methane, ammonia, nitrogen and water. It also is home to the known dwarf planets Pluto, Haumea and Makemake. The Kuiper-Edgeworth Belt is named for the astronomers Gerard Kuiper. The Kuiper Belt extends from roughly the orbit of Neptune (at 30 AU out to about 55 astronomical units) from the Sun. Oort cloud: The Oort cloud is an extended shell of icy objects that exist in the outermost reaches of the solar system. It is named after astronomer Jan Oort, who fi rst theorized its existence. The Oort cloud is roughly spherical, and is thought to be the origin of most of the long-period comets that have been observed. Objects in the Oort cloud are also referred to as Trans-Neptunian objects. This name also applies to objects in the Kuiper Belt. Korolev Crater About: European Space Agency’s (ESA) Mars Express mission has discovered an icy crater on Mars which has been named as Korolev Crater. TARGET PT 2020 7 Korolev Crater has been located by Mars Express Mission near the north pole of the Red Planet It is fi lled with a mound of water ice 60 kilometers across and nearly 2 kilometers thick. The water ice is a permanent feature. It has been anticipated that the crater traps a layer of cold air that prevents the ice melting even during the six-month-long northern summer on Mars, making this a yearlong winter wonderland. Signifi cance: Water on Mars has long been debated as the sign of existence of life on Mars, further existence of this huge reservoir of water will give thrust to it. To date, no proof has been found of past or present life on Mars but Cumulative evidence shows that during the ancient Noachian time period, the surface environment of Mars had liquid water and may have been habitable for microorganisms. Although, the existence of habitable conditions does not necessarily indicate the presence of life. THE EARTH Earth is the third planet from the Sun and is the largest of the terrestrial planets. The Earth is the only planet in our solar system not to be named after a Greek or Roman deity. In size, it is the fi fth largest planet. It is slightly fl attened at the poles. That is why its shape is described as a Geoid. The Moon (or Luna) is the Earth’s only natural satellite. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth. Evidence of the Earth’s Sphericity Ship’s visibility: When a ship appears over the distant horizon, top of the mast is seen before the hull & vice a versa. Sunrise & Sunset: Sun rises & sets at different times in different places. As earth rotates from west to east, places in east see sun earlier than those in the west. Lunar eclipse:Shadow cast by earth on the moon during the lunar eclipse is always circular. Driving poles on level ground on curved earth: Engineers while driving poles of equal length at regular intervals on the ground have found that they do not give a perfect horizontal level. Centre pole normally projects slightly above the poles at either end because of curvature of the Earth. Hence they have to make certain corrections for this inevitable curvature i.e. 8” to a mile. Aerial Photographs: Pictures taken from high altitudes by rockets & satellites show clearly the curved edge of the earth. This is perhaps the most convincing & up to date proof of earth’s sphericity. Latitudes and Longitudes Latitudes: The Equator is an imaginary line around the middle of the Earth. It is halfway between the North and South Poles, and divides the Earth into the Northern and Southern Hemispheres. The Earth is widest at its Equator. The distance around the Earth at the Equator, its circumference, is 40,075 kilometers (24,901 miles). Orbital plane is the plane formed by the orbit. The axis of the Earth is an imaginary line that makes an angle of 66½° with its orbital plane. Latitudes and Longitudes are imaginary lines used to determine the location of a place on earth. Parallels of Latitudes are the angular distance of a point on the earth’s surface, measured in degrees from the center of the Earth. As the earth is slightly fl attened at the poles, the linear distance of a degree of latitude at the pole is a little longer than that at the equator. Besides the equator (0°), the north pole (90°N) and the south pole (90°S), there are four important 8 TARGET PT 2020 parallels of latitudes– ! Tropic of Cancer (23½° N) in the Northern Hemisphere. ! Tropic of Capricorn (23½° S) in the Southern Hemisphere. ! Arctic Circle at 66½° North of the Equator. ! Antarctic Circle at 66½° South of the Equator. Latitudinal Heat zones of the Earth The mid-day sun is exactly overhead at least once a year on all latitudes in between the Tropic of Cancer and the Tropic of Capricorn. This area, therefore, receives the maximum heat and is called the Torrid Zone. The mid-day sun never shines overhead on any latitude beyond the Tropic of Cancer and the Tropic of Capricorn. The angle of the sun’s rays goes on decreasing towards the poles. As such, the areas bounded by the Tropic of Cancer and the Arctic circle in the northern hemisphere, and the Tropic of Capricorn and the Antarctic circle in the southern hemisphere, have moderate temperatures. These are, therefore, called Temperate Zone. Areas lying between the Arctic circle and the north pole in the northern hemisphere and the Antarctic circle and the south pole in the southern hemisphereare very cold.

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