WORLD GEOGRAPHY

UNIVERSE

The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. While the spatial size of the entire Universe is unknown, it is possible to measure the size of the observable universe, which is currently estimated to be 93 billion light years in diameter. In various multiverse hypotheses, a universe is one of many causally disconnected constituent parts of a larger multiverse, which itself comprises all of space and time and its contents.

SOLAR SYSTEM

The System comprises the Sun and its eight planets, which are believed to have been developed from the condensation of gases and other lesser bodies.

MAJOR COMPONENTS OF THE SOLAR SYSTEM

The Sun and the collection of all of its companions that travel through space together along with it is known as the Solar System. There are a variety of objects in the Solar System.

Planets: There are ten planets in the Solar System. Five of them are visible from Earth without using a telescope. Historically, the Sun, Moon and the five visible planets were used as the sources for the names for the seven days of the week.

Satellites: Most of the planets have satellites. The satellite that revolves around the Earth is called the Moon. Mars has two satellites. Even some asteroids have satellites.

Asteriods: Asteriods are smaller than planets. They are located mainly in the asteroid belt which which is found between the orbits of Mars and Jupiter.

Comets: Comets are objects consisting of frozen molecules of gases and other solid materials. The period of a comet refers to how long it takes the comet to revolve around the Sun. Some comets have very, very long periods. Halley's Comet has a period of about 76 years.

Meteoroids: A meteoroid is an interplanetary particle in the Solar System. When a meteoroid enters the Earth's atmosphere it heats up and evaporates producing a streak of light called a meteor. Sometimes they come in groups called meteor showers. If a meteor reaches the ground then it is called a meteorite. Some really large meteors have impacted the Earth. One produced the Meteor Crater in Arizona.

Dust: The inner Solar System contains a vast cloud of very small dust particles. On a really clear night it can be seen as a glow in the west just at the end of twilight, provided there are not too many street lights around.

PLANETS

The planets are the major components of the Solar System. The table below gives the approximate mass of each body in comparison to the mass of the Earth.

Solar System Object Mass (in relation to Earth) Sun more than 300,000 times heavier than the Earth Mercury 1/18 of the mass of the Earth Venus 1/1.22 (80%) of the mass of the Earth Earth 1 Moon 1/81 of the mass of the Earth Mars 1/9 of the mass of the Earth Jupiter 318 times the mass of the Earth Saturn 95 times the mass of the Earth Uranus 15 times the mass of the Earth Neptune 17 times the mass of the Earth Pluto 1/400 of the mass of the Earth Sedna ?

The Sun is more than 300,000 times as massive as the Earth. It is the largest and most massive object in the Solar System. Pluto has 1/400 of the mass of the Earth. It is the least massive of the planets. THE PLANETS IN SEQUENCE One of the important skill areas in K-4 for Standard 11 is that the students should be able to make a model showing the planets in correct sequence. The planets are briefly described below in the sequence in which they are found in the Solar System. Mercury  Mercury is the closest planet to the Sun.  The mass of Mercury is much smaller than that of the Earth. Mercury has about 1/9 of the mass of the Earth. Venus  Venus is the second planet from the Sun.  The mass of Venus is almost the same as that of the Earth. Venus has about 82% of the mass of the Earth. Earth  Earth is the third planet from the Sun.  Earth has one satellite called the Moon. The mass of the Moon is 1/81 of the mass of the Earth.

Mars  Mars is the fourth planet from the Sun.  The mass of Mars is about 1/9 of the mass of the Earth. Jupiter  Jupiter is the fifth planet from the Sun.  Jupiter is the largest planet. Its mass is 318 times the mass of the Earth.

Saturn  Saturn is the sixth planet from the Sun.  The mass of Saturn is 95 times the mass of the Earth. Uranus  Uranus is the seventh planet from the Sun.  The mass of Uranus is about 15 times the mass of the Earth. Neptune  Neptune is the eighth planet from the Earth.  The mass of Neptune is about 17 times the mass of the Earth. Pluto  Pluto is the ninth planet from the Earth.  Pluto is very tiny. It has the smallest mass of any of the planets. It is about 1/400 of the mass of the Earth. Sedna  Sedna was discovered photographically in 2003 and announced in 2005. ORIGIN OF EARTH Earth, along with the other planets, is believed to have been born 4.5 billion years ago as a solidified cloud of dust and gases left over from the creation of the Sun. For perhaps 500 million years, the interior of Earth stayed solid and relatively cool, perhaps 2,000°F. The main ingredients, according to the best available evidence, were iron and silicates, with small amounts of other elements, some of them radioactive. As millions of years passed, energy released by radioactive decay—mostly of uranium, thorium, and potassium—gradually heated Earth, melting some of its constituents. The iron melted before the silicates, and, being heavier, sank toward the center. This forced up the silicates that it found there. After many years, the iron reached the center, almost 4,000 mi deep, and began to accumulate. No eyes were around at that time to view the turmoil that must have taken place on the face of Earth—gigantic heaves and bubblings on the surface, exploding volcanoes, and flowing lava covering everything in sight. Finally, the iron in the center accumulated as the core. Around it, a thin but fairly stable crust of solid rock formed as Earth cooled. Depressions in the crust were natural basins in which water, rising from the interior of the planet through volcanoes and fissures, collected to form the oceans. Slowly, Earth acquired its present appearance.

SUN

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers (864,000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally and not completely accurately referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process. EARTHQUAKES

Earthquakes are caused by the movement of the earth's tectonic plates. Earthquakes occur where the earth's plates meet along plate boundaries (see plate tectonics page for more information on this).For example as two plates move towards each other, one can be pushed down under the other one into the mantle. If this plate gets stuck it causes a lot of pressure on surrounding rocks. When this pressure is released it produces shock waves. These are called seismic waves. This is an earthquake. The waves spread out from the point where the earthquake started - the focus. More damage is done near the focus. The point on the earth's surface directly above the focus is the epicentre.

Effects of Earthquakes

The effects of earthquakes vary. This is a result of a variety of factors such as the strength of the earthquake, the level of population in an area and the level of economic development of the area struck.

Measuring Earthquakes The magnitude (size) of an earthquake is measured using a seismometer. This is a machine that measures movements in the earth's surface.

The Richter Scale measures earthquakes on a logarithmic scale - this means that an earthquake of 6 is ten times more powerful than one with a score of 5.

ROCKS

A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed. Rocks are usually grouped into three main groups: I. Igneous rocks II. Metamorphic rocks and III. Sedimentary rocks Igneous rock Formed due to the cooling, solidification and crystallisatiioin of hot and molten magma. They are called as the Primary rocks as all the other rocks are formed directly or indirectly from the igneous rocks. They are hard, granular and crystalline rocks, less affected by chemical weathering. Moreover, it does not have any fossil or does not form any strata or layers of lava, eg, of Igneous rocks – Granite, Loccolith, Batholiths, Sills, Basalt, Gabbro. Metamorphic rocks

Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous rock or another older metamorphic rock—to different temperature and pressure conditions than those in which the original rock was formed. This process is called metamorphism, meaning to "change in form". The result is a profound change in physical properties and chemistry of the stone. The original rock, known as the protolith, transforms into other mineral types or other forms of the same minerals, by recrystallization. The temperatures and pressures required for this process are always higher than those found at the Earth's surface: temperatures greater than 150 to 200 °C and pressures of 1500 bars. Metamorphic rocks compose 27.4% of the crust by volume.

Sedimentary rocks

Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particles and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. LANDFORM

Many different types of landforms make up Earth‘s topography. Several major categories of landform define that smaller portion of the planet not covered by water, including mountains, plains, plateaus and valleys. These can be formed by a variety of natural forces, including erosion from water and wind, plate movement, folding and faulting, and volcanic activity. Mountain

The most common type of mountains arise where the Earth‘s crust experienced folding or faulting, such as the Canadian Rockies and the Alps. Fault-block mountains, such as California‘s Sierra Nevada, are formed when Earth‘s crust cracked and was pushed upward. Volcanic mountains form when hot magma from deep in Earth‘s interior breaks through the

crust and builds up on the surface, whether quietly or explosively. Volcanism can form islands, such as Hawaii, built on a series of broad basaltic shield volcanoes. Volcanoes on continents can also appear isolated and almost island-like given their prominence, a prime example being Washington State‘s Mount Rainier.

Plains

Most of the Earth's surface consists of low and high plains, defined by a mostly level profile that ranges from gently rolling to completely flat. Such landforms are common in areas of extensive sediment accumulation, as in the ―floodplains‖ and deltas of large rivers and the Atlantic-Gulf Coastal Plain of the United States. While those examples are low-lying, higher-elevation plains such as the Great Plains of central North America – built by sediment washed out of the Rocky Mountains and accumulated in long-ago seaways – also exist. Keep in mind that plains describe mostly level topography, though people sometimes incorrectly use ―plain‖ as a synonym for grassland ecosystems (prairies and steppes). You can easily have a forested plain.

Valleys, Canyons and Caves The erosion of rivers and the moving ice bodies called glaciers help sculpt valleys, often in combination with faulting. Glaciers flowing down drainages tend to sculpt U-shaped valleys; such glacially carved troughs often come to support lakes, as in the Finger Lakes of New York State. Running water, by contrast, tends to carve out V-shaped valleys.

Mountain valleys tend to have steep walls and narrow channels – such features may be called canyons or gorges – while valleys on plains tend to have shallow slopes and wider channels. Caves form in karsts, where limestone, dolomite, or gypsum rocks are slowly dissolved by groundwater. Others are formed by waves pounding cliffs on the coastlines, or where molten rock drains out the inside of a lava tube of a volcano. Deserts

The ecological landscapes known as deserts, defined by very arid conditions of low precipitation and high evaporation, include plentiful mountains, plains, plateaus and canyons that include distinctive sub-varieties of desert landforms. These include gravel plains, sand dunes and dry lakebeds. Many natural factors are responsible for the creation of deserts, particularly current and past climatic conditions. The Mojave Desert in California consists of 1.6 million acres of landscapes that changed over millions of years, including mountains, canyons, volcanic fields and dry lake basins. The region is within a great inland drainage basin where ancient lakes overflowed into adjacent valleys and eventually spilled into Death Valley. After the region dried up, it left dry lakebeds exposed to erosion by the wind.

IMPORTANT BOUNDARY LINES

Durand Line is the line demarcating the boundaries of Pakistan and Afghanistan. It was drawn up in 1896 by Sir Mortimer Durand. Hindenburg Line is the boundary dividing Germany and Poland. The Germans retreated to this line in 1917 during World War I Mason-Dixon Line is a line of demarcation between four states in the United State. Marginal Line was the 320-km line of fortification on the Russia-Finland border. Drawn up by General Mannerheim. Macmahon Line was drawn up by Sir Henry MacMahon, demarcating the frontier of India and China. China did not recognize the MacMahon line and crossed it in 1962. Medicine Line is the border between Canada and the United States. Radcliffe Line was drawn up by Sir Cyril Radcliffe, demarcating the boundary between India and Pakistan. Siegfried Line is the line of fortification drawn up by Germany on its border with France.Order-Neisse Line is the border between Poland and Germany, running along the Order and Neisse rivers, adopted at the Poland Conference (Aug 1945) after World War II. 17th Parallel defined the boundary between North Vietnam and South Vietnam before two were united. 24th Parallel is the line which Pakistan claims for demarcation between India and Pakistan. This, however, is not recognized by India 26th Parallel south is a circle of latitude which crosses through Africa, Australia and South America. 30th Parallel north is a line of latitude that stands one-third of the way between the equator and the North Pole. 33rd Parallel north is a circle of latitude which cuts through the southern United States, parts of North Africa, parts of the Middle East, and China. 35th Parallel north forms the boundary between the State of North Carolina and the State of Georgia and the boundary between the State of Tennessee arid the State of Georgia, the State of Albama, and the State of Mississippi. 36th Parallel forms the southernmost boundary of the State of Missouri with the State of Arkansas. 36o30′ Parallel north forms the boundary between the Tenessee and the Commonwealth of Kentucky between the Tennessee River and the Mississippi River, the boundary between Missouri and Arkansas west of the White River, and the northernmost boundary between the Texas and the Oklahoma. 37th Parallel north formed the southern boundary of the historic and extralegal Territory of Jefferson. 38th Parallel is the parallel of latitude which separates North Korea and South Korea. 39th Parallel north is an imaginary circle of latitude that is 39 degrees north of Earth‘s equatorial plane. 40th Parallel north formed the original northern boundary of the British Colony of Maryland. 41st Parallel north forms the northern boundary of the State of Colorado with Nebraska and Wyoming and the southern boundary of the State of Wyoming with Colorado and Utah. 42nd Parallel north forms most of the New York – Pennsylvania Border. 43rd Parallel north forms most of the boundary between the State of Nebraska and the State of South Dakota and formed the northern border of the historic and extralegal Territory of Jefferson.

The Parallel 44o north is an imaginary circle of latitude that is 44 degrees north of the Earth‘s equatorial plane.

45th Parallel north is often the halfway point between the Equator and the North Pole. The 45th parallel makes up most of the boundary between Montana and Wyoming. 49th Parallel is the boundary between USA and Canada.

HIGHEST & LOWEST POINTS OF CONTINENTS

1. Asia Highest Point : Mt. Everest (8848 m) Lowest Point : Dead Sea (-396.8 m) 2. Africa Highest Point : Mt. Kilimanjaro (5895 m) Lowest Point : Lake Assal (-156.1 m) 3. North America Highest Point : Mt. Mckinley (6194 m) Lowest Point : Death Valley (-85.9 m) 4. South America Highest Point : Aconcagua (6960 m) Lowest Point : Valdis Penin (-39.9 m) 5. Europe Highest Point : Elbrus (5663 m) Lowest Point : Caspian Sea (-28.0 m) 6. Australia Highest Point : Koscisko (2228 m) Lowest Point : Lake Eyre (-15.8 m) 7. Antarctica Highest Point : Vinson Massif (4897 m) Lowest Point : Bentlay Trench (-2555 m)