indian and world geography - unique shiksha

Indian and World Geography

Topic-wise Strategy

Part A: World Geography

1. The Universe 1

1. Origin of the Universe 12. Solar System 13. The Sun 2

3.1 Mercury 33.2 Venus 33.3 Earth and the Moon 33.4 Mars 33.5 Asteroid Belt 43.6 Jupiter 43.7 Saturn 43.8 Uranus 53.9 Neptune 53.10 Glossary 5

Self–Evaluation Test 7

2. The Earth 8

1. Theories on the Origin of the Earth 82. Place of the Earth in the Universe 83. Position, Shape and Size 9

3.1 Earth as an Oblate Spheroid 94. Motions of the Earth and their

Consequences 94.1 Rotation 94.2 Revolution 104.3 Apparent Migration of the Sun 11

5. The Earth’s Grid System 125.1 Latitude 125.2 Longitude 125.3 Longitudes and Time Zones 13

6. Years, Months and Calendars 147. The Moon, Blood Moon and

Red Moon 157.1 Phases of Moon 167.2 Types of Moon 16

8. Eclipses 168.1 Solar Eclipse 168.2 Lunar Eclipse 17


3. Geomorphology 181. Earth’s Geological Time Scale 182. Interior of the Earth 193. Information Sources About

Earth’s Interior 203.1 Direct Sources 203.2 Indirect Sources 21

4. The Theory of Continental Drift 214.1 Evidences in Support of the

Continental Drift 225. The Theory of Plate Tectonics 22

5.1 SeafloorSpreading 225.2 EvidenceforSeafloorSpreading 23

6. Volcanoes 256.1 Magma 256.2 Types of Volcanoes 256.3 World Distribution of Volcanoes 26

7. Earthquakes 277.1 Distribution of Earthquakes 277.2 Types of Earthquake Waves 287.3 Risk Zone 28

8. Rocks 288.1 ClassificationofRocks 288.2 Rock Cycle 31

Indian and World Geography 1-276

Contents

9. Endogenic Forces of Landforms 329.1 Nappes 339.2 Crustal Fracture 339.3 Rift Valley 33

10. Exogenic Forces of Landforms 3411. Weathering 34

11.1 Types of Weathering 3412. Major Landforms of the World 35

12.1 Mountains 3512.2 Plateaus 3612.3 Plains 37

13. Fluvial Landform 3714. Karst Landforms 3915. Coastal Landforms 4116. Aeolian Landforms 44Self–Evaluation Test 48

4. Oceanography 49

1. Oceans of the World 491.1 Continental Shelf 491.2 Continental Slope 491.3 Deep Sea Plains 501.4 Ocean Deep or Trenches 501.5 Submarine Canyons 50

2. Reliefs of Ocean: Basins 512.1 PacificOcean 512.2 Atlantic Ocean 512.3 Indian Ocean 51

3. Temperature of Ocean Water 513.1 FactorsAffectingtheTemperature

of Oceans 513.2 Vertical Distribution of Temperature 51

4. Salinity of the Oceans 514.1 PacificOcean 524.2 Atlantic Ocean 524.3 Indian Ocean 52

5. Oceanic Deposits 526. Ocean Currents 52

6.1 Atlantic Ocean 526.2 PacificOcean 536.3 Indian Ocean 53

7. Ocean Tides 547.1 Diurnal and Semi Diurnal Tides 54

7.2 Spring and Neap Tides 557.3 Cycle of Declination 55

8. Coral Reefs 558.1 Types of Coral Reefs 55

9. Mineral Resources of Oceans 5610. Ocean Energy Resources 57

10.1 Ocean Thermal Energy 5710.2 Ocean Mechanical Energy 57

11. Oil Spill 5711.1 Directly 5711.2 Indirectly 57


5. Hydrosphere 59

1. Hydrologic Cycle 592. Ocean 603. Soil Water 604. Sources of Water 60

4.1 Ground Water 604.2 Springs and Seeps 614.3 Geyser 614.4 Wells 62

5. Rivers 634.1 Parts of a River 63

6. Lakes 636.1 Characteristics of a Lake 636.2 Preconditions of a Lake 646.3 ClassificationofLakes 64


6. Atmosphere 65

1. Atmosphere 652. Composition of the Atmosphere 653. Structure of the Atmosphere 65

3.1 Troposphere 653.2 Stratosphere 663.3 Chemosphere 663.4 Mesosphere 663.5 Thermosphere 663.6 Exosphere 663.7 Homosphere 663.8 Heterosphere 67

4. Insolation and Heat Budget 674.1 Heat Budget or Heat Balance 67

5. Terrestrial Radiation 685.1 Global Heat Balance 68

6. Distribution of Temperature 686.1 Horizontal Distribution 686.2 Vertical Distribution 696.3 Temperature Zones 69

7. Pressure and Winds 707.1 Causes of Pressure Changes

andDifferences 707.2 Relation between Pressure and Wind 707.3 Seasonal Shifting of the Pressure Belts 717.4 Major Pressure Belts 71

8. Humidity and Evaporation 728.1 Latent Heat 728.2 Evaporation 728.3 Absolute Humidity 728.4 SpecificHumidity 728.5 Relative Humidity 73

9. Winds 739.1 FactorsAffectingWind 749.2 Isobars 749.3 Primary Winds 749.4 Secondary Winds 75

10. Cooling of Air and Adiabatic Change 77

11. Stability and Instability of the Atmosphere 77

12. Forms of Condensation 7812.1 Mist 7812.2 Dew 7812.3 Fog 7812.4 Frost 78

13. Clouds 7813.1 ClassificationofClouds 78

14. Precipitation 7915. Rainfall 79

15.1 Origin of Rainfall 7915.2 Pre-conditions of Condensation 79

16. Types of Rainfall 7916.1 Convectional Rainfall 7916.2 Orographic Rainfall 7916.3 Cyclonic or Frontal Rainfall 80

17. Distribution of Rainfall 8018. Major Atmospheric Disturbances 80

18.1 Fronts 8018.2 Cyclones 8118.3 Typhoons 8118.4 Thunderstorm 8118.5 Hurricanes 8218.6 Tornadoes 8218.7 Water Sprout 8218.8 Temperate Cyclone 8218.9 Anticyclone 82

19. Weather and Climate 8320. Types of Climate 83

20.1 Equatorial Climate 8320.2 Tropical Climates 8520.3 Temperate Climates 8720.4 Cool Temperate Zone 8820.5 Cold Zone 8920.6 Mountain Climate 89

21. Global Climatic Change 90Self–Evaluation Test 91

7. Population and Human Diversity 92

1. Population 922. Races of the World 923. Population Distribution 93

3.1 Densely Populated 933.2 Sparsely Populated 93

4. Demographic Transition Model 934.1 There are Four Stages of Transition 93

5. Age Sex Pyramid 946. Factors Affecting Distribution of

Population 947. Migration 95

7.1 Streams of Migration 957.2 Causes of Migration 957.3 Consequences of Migration 95


8. Continents 97

1. Introduction 972. South America 97

2.1 South America and Mexico Resources 99

3. Africa 994. Europe 101

4.1 Europe and CIS Resources 1024.2 Industrial Regions 103

5. Asia 1045.1 Asia Resources 1055.2 China 1065.3 Korea 1065.4 South East Asia 1065.5 West Asian and Other Asian Countries 106

6. North America 1076.1 North America Resources 1086.2 Industrial Regions 1096.3 Canada 1096.4 Industrial Regions 110

7. Australia 1108. Antarctica 1119. Road Transport 11410. Rail Transport 11411. Ocean Transport: Major

Trade Routes 114Self–Evaluation Test 115

9. Natural Resources 116

1. Classification ofNatural Resources 1162. Soils 117

2.1 Soil Pedogenesis 1172.2 Physical and Chemical Properties of Soil 1182.3 Themodifiedmarbutsystemdivides

the soil into three broad groups or zonal orders 118

2.4 Soil Horizons 1193. Principal Pedogenic Processes

(Soil Forming Processes) 1204. Flora and Fauna 120

4.1 Biome 1204.2 Monsoon Deciduous Forests 1204.3 Savanna Biome 1224.4 Mediterranean Biome 1224.5 Temperate Grassland Biome 1224.6 Boreal Forest Biome or Taiga Biome 1224.7 Tundra Biome 122

5. Natural Regions of the World 1225.1 Equatorial Region 1225.2 Savanna Region 1235.3 Hot Desert Region 1235.4 Mediterranean Region 1235.5 Temperate Grassland 1235.6 Coniferous Forests 1245.7 Tundra Region 124


10. Agriculture 126

1. Agriculture Production Practices 1261.1 Climate change 1261.2 Deforestation 1261.3 Irrigation 1271.4 Pollutants 1271.5 Soil Degradation 1271.6 Nutrient Management in Agriculture 1271.7 Indiscriminate Use of Fertilizers and

itsEffects 1281.8 Pollution by Indiscriminate use of Urea 1281.9 Pollution by Indiscriminate Use

of Phosphorus 1281.10 Indiscriminate Use of Potassium 128

2. Vermicompost 1282.1 BenefitsofVermicompostforSoil 1282.2 EnvironmentalBenefitsof

Vermicompost 1282.3 Disadvantages / Issues of

Vermicompost: 1293. Biofertilizers 129

3.1 Biopesticides 1293.2 Bioherbicides 1293.3 Bioinsecticide 1293.4 Examples of Biopesticides 129

4. Modern Agriculture 1294.1 Plantation Agriculture 130

5. Fisheries 1305.1 Types of Fishes 1305.2 Major Fishing Zones 130


Part B: Indian Geography

1. Physiography of India 132

1. General Data 1321.1 Size and Location 1321.2 Indian Ocean 1321.3 India and the World 1331.4 Locational Advantage 1341.5 Political Divisions of India 134

2. India’s Geological Eras 1343. Geological History of India 134

3.1 The Peninsular Plateau 1343.2 The Himalayas 1363.3 Evolution of Surface Features 139

4. Major Divisions 1394.1 The Northern Mountains 1394.2 The Indus-Ganga Brahmaputra Plain 1424.3 Peninsular Plateau 1424.4 The Great Indian Desert 1454.5 The Islands 145


2. India’s Drainage System 148

1. India’s Water Resources 1482. Sources of Water 148

2.1 Precipitation 1492.2 Surface Water 1492.3 Ground Water 149

3. Drainage Pattern 1504. India’s Drainage System 1515. The Himalayan Rivers 151

5.1 The Indus System 1515.2 The Ganga System 1525.3 The Brahmaputra River System 153

6. The Peninsular Rivers 1547. Major Rivers of the Peninsular

Plateau 1547.1 ClassificationofPeninsularRivers 157

8. Drainage of the Thar Desert Region 157

9. The River Regimes 15710. Lakes 15711. Watershed Development 157Self–Evaluation Test 160

3. Climate of India 161

1. Introduction 1612. Factors Affecting the Climate

of India 1613. Monsoon Winds and its

Various Aspects 1624. Seasons in India 164

4.1 The Cold Weather Season (Northeast Monsoons) 164

4.2 The Hot Weather Season 1644.3 The South-West Monsoon Season 1644.4 The Retreating South West

Monsoon Season 1655. Modern Explanation of Monsoon 166

5.1 Winter 1665.2 Spring 1665.3 Summer 1665.4 Autumn 167

6. Distribution of Rainfall in India 1676.1 Variability of Rainfall 1676.2 Spatio Temporal Variation in

the Rainfall 1677. Climatic Regions of India 168

7.1 Koppen’sClimaticClassification 1687.2 Moisture Index of Thornthwaite 169

8. The El-nino and La-Nina Effect 1699. Indian Ocean Dipole 170

9.1 Negative IOD Phase 1709.2 Neutral IOD Phase 1719.3 Positive IOD Phase 171


4. Natural Vegetation 173

1. India’s Natural Vegetation 1732. Floristic Regions of India 173

3. India’s Forest Cover 1744. Mangrove Cover 1775. Afforestation and Re-afforestaion 1776. Social Forestry 1777. CAMPA Bill 178Self–Evaluation Test 178

5. Soils of India 179

1. Classification of Soil 1791.1 ICARClassification 1791.2 Alluvial Soil 1791.3 Red and Yellow Soil 1801.4 Black or Regur Soils 1801.5 Laterite Soil 1801.6 Saline or Alkaline Soil 1811.7 Mountain Soil 1811.8 Desert Soil 1811.9 Peaty and Marshy Soil 182

2. Pattern of Soil Erosion 1823. Soil Conservation 182Self–Evaluation Test 185

6. The People of India 186

1. Ethnic Diversities 1861.1 Racial Groups of India Given

by R.S. Guha 1862. Tribal Population of India 1863. Population of India 187

3.1 Population Highlights 1873.2 Population (0–6 years) Highlights 1883.3 Sex Ratio (0–6 years) Highlights 1893.4 Literacy 1893.5 Density of Population 189


7. Mineral & Power Resources of India 191

1. Mineral Resources 1911.1 Mineral Belts in India 192

2. Distribution of Mineral Resources 1922.1 Iron Ore 1922.2 Manganese 1932.3 Bauxite 1932.4 Lead 1932.5 Zinc 1932.6 Copper Ore 1932.7 Limestone 1932.8 Dolomite 1942.9 Magnesite 1942.10 Kyanite 1942.11 Sillimanite 1942.12 Phosphate 1942.13 Common Salt 1942.14 Sulphur 1942.15 Gold 1942.16 Mica 1942.17 Atomic Minerals 194

3. Shale Gas in India 1944. Lignite and Coal 197

4.1 Lignite 1974.2 Coal 1974.3 CoalClassificationBasedon

Carbon Content 1974.4 ImportantCoalfields 1974.5 Peat 198

5. Petroleum 1985.1 On-Shore Oil Production in India 1985.2 Off-ShoreProductioninIndia 198

6. Gas Grid 2007. Regasification Infrastructure

in the Country 2008. City Gas Distribution (CGD) 2009. Hydroelectric Power Plants 20110. Thermal Power 20111. Atomic Power Plants 20212. Different Forms of Renewable

Energy 202Self–Evaluation Test 205

8. Agriculture in India 206

1. Agricultural Seasons of India 2082. Mixed Cropping Pattern 2083. Major Food Crops 2084. Green Revolution in India 210

4.1 Components of Green Revolution 2104.2 Impact of Green Revolution 210

5. Vegetables 2116. Floriculture 2117. Medicinal and Aromatic Plants 2128. Varieties of Crops 2129. Livestock 212

9.1 Cattle 2129.2 Buffalo 2139.3 Sheep 213

10. Environmental Impact of Agriculture 21410.1 Climate Change 21410.2 Deforestation 21410.3 Irrigation 21410.4 Pollutants 21410.5 Soil Degradation 214

11. Land Resources 215Self–Evaluation Test 216

9. Natural Disaster and its Management 217

1. Introduction 2171.1 Indian Scenario 2171.2 List of Various Disasters 2181.3 VulnerabilityProfileofIndia 2181.4 HazardProfileofIndia 218

2. Drought 2183. Floods 2194. Tropical Cyclones 2195. Heat Wave 221

5.1 Health Impacts of Heat Waves 2226. Earthquakes 2227. Thunderstorm, Hailstorm and

Dust Storm 223

8. Cold Wave and Fog 2239. Landslides 22410. Tsunami 22411. Industrial and Chemical Disasters 22412. Stampede 22513. Road Accidents 22514. Mine Disasters 22515. Forest Fire 22516. Epidemics in India 22517. Nuclear Emergencies 22618. Regulatory Measures 226

18.1 Present Structure for Disaster Management in India 226

18.2 Preparedness, Mitigation and Prevention 226

19. National Disaster Management Act 2005 227

20. National Disaster Management Authority 227

21. Prevention and Mitigation 22822. National Disaster Mitigation Fund 229

22.1 Role of District Administration 22922.2 National Disaster Response Force (NDRF) 230

23. Role of Local Bodies 230Self–Evaluation Test 230

10. Water Resources 231

1. Distribution of Irrigated Areas 2312. National Water Grid 2323. Sources of Irrigation 2334. Multi-Purpose Projects 235

4.1 Some Major Irrigation/ Multipurpose Projects 235

5. Rivers Interlinking Project 238Self–Evaluation Test 239

11. Industry 240

1. Geographical Factors for the Location of Industries 240

2. Industrial Regions of India 241

2.1 Mumbai-Pune Industrial Region 2412.2 Hugli Industrial Region 2412.3 Bengaluru-Chennai Industrial Region 2422.4 Gujarat Industrial Region 2422.5 Chotanagpur Region 2422.6 Vishakhapatnam-Guntur Region 2432.7 Gurgaon-Delhi-Meerut Region 243


12. Transportation in India 246

1. Road Transport 2461.1 Golden Quadrilateral Super Highways 2461.2 National Highways 2461.3 State Highways 2461.4 District Roads 2461.5 Other Roads 2461.6 Border Roads 2461.7 Road Density 248

2. Bharatmala Pariyojana 2502.1 Highlights of Bharatmala Pariyojana 2502.2 Bharatmala Project Category 250

3. Railways 2503.1 Gauges of Indian Railways 251

4. Water Transport 2514.1 Shipping 2514.2 Development of Gateway Ports 2524.3 Sagarmala Project 2524.4 National Waterways 2524.5 Inland Port 254

5. Air Transport 2555.1 Problems of Air Transport In India 2555.2 Regional Connectivity Scheme “UDAN” 255

6. Pipelines 2566.1 Petroleum Product Pipelines 256


Practice Set-World Geography 260Practice Set-Indian Geography 268

1. Origin Of the Universe

The Universe is the sum total of all existence. It is the entirety of time, space, matter and energy, that began expanding some 13.8 billion years ago and has continued to expand ever since. No one is entirely certain how extensive the Universe truly is, and no one is entirely sure how it will all end.

The Big Bang hypothesis states that all of the current and past matter in the Universe came into existence at the same time, roughly 13.8 billion years ago. At this time, all matter was compacted into a very small ball with infinite density and intense heat called a Singularity. Suddenly, the Singularity began expanding and the universe, as we know it began.

This theory also accounts for the expansion of the Universe, the existence of the Cosmic Microwave Background, and a broad range of other phenomena.

What is a Singularity?

In scientific terms, a gravitational singularity (or space-time singularity) is a location where the quantities, that are used to measure the gravitational field, become infinite in a way that does not depend on the coordinate system. In other words, it is a point in which all physical laws are indistinguishable from one another, where space and time are no longer interrelated realities, but merge indistinguishably and cease to have any independent meaning.

2. sOlar system• The solar system is made up of the Sun and everything that

orbits around it, including Planets, Moons, Asteroids, Comets and Meteoroids.

• Many scientists think that our Solar system was formed from a giant, rotating cloud of gas and dust, known as the Solar Nebula. As the nebula collapsed because of its gravity, it spun faster and flattened into a disk. Most of the material was pulled toward the center to form the Sun. Other particles within the disk collided and stuck together to form asteroid-sized objects named as planetesimals, some of which combined to become the asteroids, comets, moons and planets.

• The solar wind from the Sun was so powerful that it swept away most of the lighter elements, such as hydrogen and helium, from the innermost planets, leaving behind mostly small, rocky worlds. The solar wind was much weaker in the outer regions, however, resulting in gas giants made up mostly of hydrogen and helium.

Part (A) World Geography

Chapter 1 The Universe

The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The study of the Universe and mainly that of the solar system is must to understand the formation and pattern of the Earth. Hence, this chapter discusses about the basic principles related to the Universe and salient features of our solar system.Through this chapter students will be able to understand:� About the Universe � Big Bang Theory� Solar System � Facts about different Planets� Terminology associated with Universe

Indian and World Geography2

Important Facts

• The star closest to the Earth: Proxima Centauri• The outermost layer of the Sun: Corona (visible only

during an eclipse)• Planets rotate from east to west: Venus and Uranus• Inner planets: Mercury, Venus, Earth and Mars• Outer Planets: Jupiter, Saturn, Uranus and Neptune• Smallest planet of the Solar System: Mercury• Brightest planet of the Solar System: Venus• Evening or morning star or twin of the Earth: Venus• Blue planet (due to presence of water): Earth• Red or fiery planet: Mars• Dusty planet: Mars• Largest planet: Jupiter• Fastest rotating planet: Jupiter• Slowest rotating planet: Venus• The outermost planet visible to the naked eye: Saturn• Planet which is known as a lying one: Uranus• Planets according to the distance from the Sun: Mercury,

Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune• Planets in order to distance from the Earth: Venus, Mars,

Mercury, Jupiter, Saturn, Uranus and Neptune• Planets according to size (descending order): Jupiter,

Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury• Some Dwarf planets ordered in their distance from Sun

are: Ceres, Pluto, Haumea, Makemake, Eris.

Planets and their SatellitesPlanets Important Satellites

1. Earth Moon (Asteroids 3753 Cruithne and 2002AA29 have complicated orbital relationship with the Earth)

2. Mars Phobos, Deimos3. Jupiter Cailesto Himalaya, Elara, Europa, Ganymede,4. Saturn Atlas, Titan, Tenthis, Phoebe, Ria, Helen5. Uranus Miranda, Titenia, Belinda, Arial6. Neptune Titan, Nerid

3. the sUn

• The Sun is by far the largest object in our Solar System, containing 99.8 percent of the solar system’s mass.

• It sheds most of the heat and light that makes life possible on Earth and possibly elsewhere.

• Planets orbit the Sun in an oval-shaped paths called ellipses, with the Sun slightly off-center of each ellipse.

• The Sun is at present, about 70 per cent hydrogen and 28 per cent helium by mass everything else (“metals”) amounts to less than 2 per cent. This changes slowly over time as, the Sun converts hydrogen to helium in its core.

• The outer layers of the Sun exhibit differential rotation: at the equator the surface rotates once every 25.4 days; near the poles it’s as much as 36 days. This odd behavior is due

to the fact that the Sun is not a solid body like the Earth. The differential rotation extends considerably down into the interior of the Sun but the core of the Sun rotates as a solid body.

Projects to study the Sun

A. Parker Solar Probe: Mission to Touch the SunIt is NASA’s first planned robotic spacecraft to study outer corona of the Sun. It is named after solar astrophysicist Eugene Parker, first spacecraft of NASA to be named after living person.Scientific Goals of PSP• Determine structure and dynamics of magnetic fields at

sources of solar wind.• Trace flow of energy that heats Corona and accelerates solar

wind.• Determine what mechanisms accelerate and transport

energetic particles.• Explore dusty plasma near the Sun and its influence on solar

wind and energetic particle formation.Its data will also be useful in improving forecasts of major eruptions on the Sun and subsequent space weather events that impact technology on Earth, as well as satellites and astronauts in space.

B. Aditya-L1 missionAditya-L1 is the India’s first dedicated scientific mission, which aims to send a satellite to study the dynamics of Sun’s Chromosphere. The mission is a joint venture between ISRO and physicists from various institutes including Indian Institute of Astrophysics, Bengaluru; Inter University Centre for Astronomy and Astrophysics, Pune; and Tata Institute of Fundamental Research, Mumbai.Objectives• The objective of the mission is to study the dynamic

nature of the Sun’s outer most layers, the Corona and the Chromosphere, and collect data about Coronal Mass Ejections (CME).

• It will also study on the origin of solar storms and their path through the interplanetary space from the Sun to the Earth.

• The studies will also focus on collection of information for space weather prediction.

SignificanceThis mission will present clear picture of Sun’s Chromosphere, which in turn will help us to understand the concept of Sun’s Corona visible during solar eclipse. Furthermore, it will help to study the discharging of charged particles into space which affect the environment there, called solar wind. Solar winds are responsible for damage to satellites and affect the upper atmosphere, but Van Allen belt protects Earth’s atmosphere from getting affected by solar winds.

• The Sun’s power (about 386 billion billion mega Watts) is produced by nuclear fusion reactions.

• The surface of the Sun, called the Photosphere, is at a temperature of about 5800 K.

• Sunspots are “cool” regions, only 3800 K (they look dark only by comparison with the surrounding regions). Sunspots are

3 The Universe

complicated and not very well understood interactions with the Sun’s magnetic field.

• A small region known as the Chromosphere lies above the Photosphere. The highly rarefied region above the Chromosphere, called the Corona, extends millions of kilometers into space but is visible only during a total solar eclipse. Temperatures in the Corona are over 1,000,000 K.

• The Sun’s magnetic field is very strong (by terrestrial standards) and very complicated. Its Magnetosphere (also known as the Heliosphere) extends well beyond Pluto.

• In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind, which propagates throughout the Solar System at about 450 km/sec. The solar wind and the much higher energy particles ejected by solar flares can have dramatic effects on the Earth, ranging from power line surges to radio interference to the beautiful aurora borealis.

3.1 Mercury• Mercury is the closest planet to the Sun. • It takes about 88 Earth days to orbit the Sun but rotates on its

axis once every 59 Earth days.• Because of the slow rotation, a single day on Mercury (mid

day to mid day) takes 176 Earth days. Its axial tilt is remarkably small at 3/100ths of a degree, much smaller than any other planet.

• Its gravity on the surface is 1/3rd of the Earth’s gravity.• Mercury has almost no atmosphere and is blasted (eroded)

by the Sun during the day and exposed to cold space during the night. This means that it undergoes some of the widest temperature variation compared to any other planet in the Solar System with temperatures reaching +430°C and dipping down to -180°C.

• It has a highly cratered rocky surface and is known to have an iron core. However its magnetic field is much weaker than the Earth’s (1 per cent as strong).

Missions to Mercury

• Before 2011, it had only been visited by 1 spacecraft - the Mariner 10 spacecraft which performed 3 fly-pasts in 1974/75 mapping about 45 per cent of its surface.

• Mercury was recently being studied by the Messenger Spacecraft. Messenger entered Mercury’s Orbit on 18th March 2011, the first manmade object ever to do so.

• The next mission to Mercury will be ESAs Bepicolumbo mission to be launched in October, 2018 and to arrive Mercury in late 2025.

3.2 Venus• Venus is the second closest planet to the Sun and orbits in an

almost circular orbit at 108 million km. • Venus takes about 225 Earth days to orbit the Sun and rotates

at the incredibly slow rate of once every 243 days - and in a clockwise direction (as seen from looking down on the Sun’s North pole). Uranus (which almost spins on its side) also has a clockwise spin.

• A day on Venus (sunrise to sunrise) lasts 117 Earth days.• Its gravity on the surface is 90 per cent that of Earth’s.• Venus atmosphere is comprised of carbon dioxide with thick

clouds of sulphur dioxide. This atmosphere has the strongest greenhouse effect known in the solar system which keeps the planet at a reasonably constant temperature of 460°C. This makes Venus the hottest planet in the Solar System, far hotter even then mercury which is twice as close to the Sun.

• Venus has a very weak magnetic field.

Mission to Venus

• In the 90’s NASA’s Magellan Spacecraft orbited the planet from 1990 to 1994, before deliberately crashing into the planet.

• Venus was last studied by Europe’s Venus Express Spacecraft, which orbited the planet from April 2006 until crashing into it sometime in January, 2015.

• Venus is currently being studied by the Japanese spacecraft Akatsuki. A rocket motor failure prevented Akatsuki from entering orbit in 2010 causing it to orbit the Sun for 5 years before being inserted into orbit in December, 2015 using its thrusters. Since May 2016 it has been carrying out scientific studies of the Venusian atmosphere.

3.3 Earth and the Moon• The third closest planet to the Sun is Earth and is the largest

and densest of the inner planets.• Earth orbits in a reasonably circular at 150 million km and is

the first of the planets to have a moon.• Earth takes 365.25 Earth days to orbit the Sun and rotates

once every 23 hours, 56 minutes and 4 seconds. Because it rotates around the Sun, the length of a day on Earth (sunrise to sunrise) takes 24 hours (approx).

• The Earth has an axial tilt of 23.4 degrees and a diameter of 12742 km.

• The Earth is thought to be 4.54 billion years old and has been accompanied by the Moon for most of that time. It is believed that the Moon was formed when a large Mars sized body impacted the Earth causing enough material to be ejected which eventually coalesced into the Moon. The Moon has had the effect of stabilising Earth’s axial tilt and is the source of the Earth’s ocean tides.

• The Moon is 3,474 km in diameter (27 per cent that of Earth) and orbits at a distance of between about 362,000 to 405,000 km. It has also been affected by the gravitational pull of the Earth, which has over time caused the Moon’s rotation to be slowed until it matches the time it takes to orbit the Earth. This is why the same side of the Moon always faces the Earth.

• Earth is protected from solar radiation by a strong magnetic field generated by movement of its core, which is mainly comprised of molten iron.

3.4 Mars• Mars is the fourth closest planet to the Sun and orbits in a

fairly eccentric orbit at around 230 (+/–20) million km.• Mars takes about 686 Earth days to orbit the Sun. • It has a tilt (25.1 degrees) and rotational period (24 hour

37 minutes), which are both similar to the Earth with a day


(sunrise to sunrise) lasting 24 hours, 39 mins. Because of the tilt it also has seasons in the same way as the Earth does.

• Mars is about half the size of the Earth with a diameter of 6,792 km. However its mass is only a tenth of Earth’s, with gravity on the surface being around 37 per cent that of Earth’s.

• Because Mars no longer has a magnetic field to protect it, Mars has lost its original atmosphere due to the effects of the solar wind interacting with the atmosphere, causing atoms to be lost into space.

• Moons: Phobos and Deimos

Mission to Mars

• The Mars Exploration Rovers, Spirit and Opportunity landed in 2004 for their 90 day mission. They both exceeded their mission objectives with Spirit eventually failing in March 2010 and Opportunity is still performing.

• Mars is currently host to seven functioning spacecraft: five in orbit – the Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, ExoMars Trace Gas Orbiter, Mars Orbiter Mission, and two on the surface – Mars Exploration Rover Opportunity and the Mars Science Laboratory Curiosity. InSight - A lander from NASA, on it’s way and due to arrive end of 2018.

Near future missions include a whole host of spacecraft to arrive 2020 to 2021:• NASA’s Mars 2020 Mission - a lander, and surprisingly

(because the atmosphere is so thin) a solar powered drone to help with navigation.

• ExoMars 2020 - the second part of ESA’s ExoMars mission to search for life. It comprises a rover to land in 2021. A public competition is open to name the rover.

• 2020 Chinese Mars Mission - An orbiter and lander to arrive in 2021.

• Hope Mars Mission or ‘Al-Amal’ - A United Arab Emirates orbiter to arrive in 2021.

• India’s Mars Orbiter Mission 2 - from the Indian Space Research Organisation. An orbiter and possible lander (2021-2022).

3.5 Asteroid Belt• Between Mars and Jupiter lies the Asteroid belt which is

comprised of thousands of rocks left over from the formation of the Solar System. These rocks vary in size from microscopic up to Ceres (950 km diameter) which is classified as a dwarf planet. Dwarf Planet is a celestial body orbiting a star that is massive enough to be rounded by its own growing but has not cleared its neighbouring region of Planetesimals and is not a satellite. It has to have sufficient mass to overcome its compressive strength and achieve hydrostatic equilibrium. It is thought that Jupiter’s strong gravitational influence may have prevented the asteroids coalescing into larger objects such as a planet.

• Outside of the asteroid belt itself there are also three clusters of asteroids which are very much in Jupiter’s influence. These are the Trojan asteroids, which orbit ahead and behind Jupiter and the Hilda Asteroids which orbit twice for every 3 Jupiter orbits. These asteroids are in Jupiter’s Lagrange points - areas of gravitational stability.

3.6 Jupiter• Jupiter is the fifth closest planet to the Sun and is the first of

what are called the outer planets (being outside the asteroid belt).

• It is by far the largest planet in the Solar System having two and a half times as much mass as all the other planets put together and one thousandth the mass of the Sun.

• Jupiter orbits the Sun once every 12 years (at about 780 million km) and is comprised of gas (75 per cent hydrogen and 24 per cent helium) and is presumed to have a rocky core surrounded by a sea of liquid metallic hydrogen which forms a ball 110,000 km in diameter. Jupiter’s total diameter is 142,984 km.

• In the upper atmosphere is a cloud layer 50 km thick. The clouds are comprised of ammonia crystals and other compounds which are arranged into bands moving at different speeds at different latitudes. The Great Red Spot is a large stable storm vortex laying between two layers.

• Considering its size, Jupiter rotates very quickly having one rotation at just under once every 10 hours. This means that at the equator there is quite a large centrifugal force, which means the planet has a pronounced bulge - its diameter around the equator is 9000 km greater than the diameter measured at the poles.

• Moons : Io, Europa, Ganymede and Callisto• Ganymede is the largest satellite in the Solar System and is

larger than the planet Mercury. It is also covered in ice but is less geologically active with its surface marked by craters and ridges.

Mission to Jupiter

• Galileo became the first spacecraft to orbit Jupiter in 1995.• The Cassini probe flew past in 2000 and imaged Jupiter’s

atmosphere revealing many unknown features.• The New Horizons probe flew past in 2007 on its way to

Pluto and studied the Jovian moons, magnetic field and ring system.

• NASA currently has a mission underway to study Jupiter in detail from a polar orbit. Named Juno, the spacecraft launched in August 2011, arrived in July 2016 and will orbit the planet until 2018 when it will be de-orbited into Jupiter. It passes very close to Jupiter on each orbit and therefore has to survive Jupiter’s intense radiation belts.

• The next planned mission to the Jovian system will be the European Space Agency’s Jupiter Icy Moon Explorer (JUICE), due to launch in 2022.

3.7 Saturn• Saturn is the sixth closest planet to the Sun. It is the second

largest planet in the Solar System having a radius 9 times that of the Earth (57,000 km) and a mass 95 times that of Earth.

• Saturn orbits the Sun once very 29 years (at about 1400 million km) and is mainly comprised of gas (96 per cent hydrogen and 3 per cent helium) and is presumed to have a rocky core surrounded by a sea of liquid metallic hydrogen, which forms a ball some 56,000 km in diameter.

• The upper layers are thought to comprise of liquid water, ammonium hydrosulfide, hydrogen and helium. Saturn’s core

5 The Universe

is quite hot (11,700 degrees C) and it generates more heat than it receives from the Sun.

• The cloud layers of Saturn are similar to those of Jupiter except that the banding is weaker and wider.

• Saturn rotates at around 10 hours 39 minutes. • Saturn’s Rings: These were first seen by Galileo Galilei in

1610 who, quite understandably, was confused by them and thought Saturn was being accompanied by two other planets which sat either side of it. The rings extend from 7000 km to 120,000 km above the surface of Saturn.

• Saturn has 62 moons with only seven being large enough to become spherical in shape. By far the largest of all of Saturn’s moons is Titan which is larger than the planet Mercury, and the second largest moon in the Solar System (Jupiter’s Ganymede being the largest).

Mission to Saturn

In 2004 the Cassini spacecraft became the first probe to enter into orbit around Saturn releasing the Huygens probe which entered Titans atmosphere early in January 2005. The Huygens probe successfully landed on the surface of Titan sending back images and data during its descent and from the surface. Cassini has made many fly-pasts of Saturn’s moons and ring systems making many new discoveries including new rings and weather systems. The Cassini spacecraft continues to study the Saturnian system until 2017 when it was deliberately crashed into Saturn.

3.8 Uranus• Uranus is the seventh closest planet to the Sun and the

third largest and fourth heaviest of the planets. It’s diameter (50,000 km) is four times that of the Earth with a mass over 14 times that of the Earth.

• Uranus orbits the Sun once every 84 years (at about 2900 million km) but is unusual with the fact that it spins on its side (with an axial tilt of 97 degrees). This means that its moons and also its faint ring system also orbit in plane perpendicular to the plane of the ecliptic.

• It is believed to be comprised of a small rocky core surrounded by a deep mantle of water, ammonia and methane. This is in turn surrounded by an atmosphere of hydrogen, helium and methane with an upper cloud layer. Another oddity in Uranus is the fact that it is very cold. All the other gas giant planets emit more heat radiation than they receive due to very hot cores, but Uranus does not. A temperature of -224°C has been measured in Uranus’ atmosphere - the coldest in the Solar System.

• Uranus’ Rings: Uranus has the second most extensive ring system of the solar system after Saturn.

• Uranus has 27 known moons with sizes ranging from over 1500 km diameter down to under 20 km. The moons consist of ice, rock and other trace elements. Some of the inner moons undergo gravitation interactions with each other which may in many millions of years lead to instabilities and collisions.

Mission to Uranus

• To date Uranus has been visited only once - by NASA’s Voyager 2 spacecraft. The fly-by occurred in 1986 and resulted in the discovery of 10 new moons and 2 rings. It also measured the chemical composition of the atmosphere and photographed the planet and its moons. This data is still being studied and in 2016 researchers claimed to have discovered evidence for two new moons which may be causing disturbances in its inner most rings.

• A “Uranus Orbiter and Probe” mission is in the study stages.

3.9 Neptune• Neptune is the eighth closest planet to the Sun and is (since

the relegation of Pluto) the last Planet in the Solar System. • It is similar in size and composition to Uranus with a diameter

of 49,000 km and a mass of over 17 times that of Earth.• Neptune orbits the Sun once every 165 years at about 4500

million km. This is 30 times the distance from the Sun to the Earth which means that the strength of sunlight at Neptune is 1 per cent of its strength at Earth. Neptune spins on an axis with a tilt of 28 degrees, which is quite similar to that of the Earth, every 16 hours.

• Unlike Uranus’ almost completely bland cloud layer, Neptune’s weather systems are more pronounced with great dark spot storm systems being seen in the southern and northern hemispheres and other visible banding.

• Neptune’s Rings: Neptune has a ring system comprised of three main rings with radii between 63,000 km and 42,000 km which appear to have a clumpy structure, in which they form arcs rather than complete rings. It is believed that gravitational effects from Neptune’s moons may cause the clumping.

• Neptune has 14 known moons of which Triton (2700 km diameter) is the most significant. The next largest moon, Proteus, is only 420 km in diameter. Triton is the only large moon to orbit in retrograde (e.g. in the opposite direction to most orbits) and is thought to be a captured object rather than created in orbit.

Mission to Neptune

• To date Neptune (like Uranus) has been visited only once - again by NASA’s Voyager 2 spacecraft. The fly-by occurred in 1989 and resulted in many discoveries including Neptune’s weather systems, rings and 6 more moons. It also provided an accurate measurement of Neptune’s mass which allowed discrepancies in the orbits of Uranus and Neptune to be solved.

• There are currently no missions planned to visit Neptune, since the Neptune Orbiter and Probe mission was dropped in favour of the Uranus Orbiter and Probe mission.

3.10 Glossary• Black Body: An idealized object that absorbs

all electromagnetic radiation which falls on it, without passing through and without reflection. The radiation emitted from a


black body is mostly infrared light at room temperature, but as the temperature increases it starts to emit visible wavelengths, from red through to blue, and then ultraviolet light at very high temperatures.

• Black Hole: The warped space-time remaining after the gravity of a massive body has caused it to shrink down to a point. It is a region of empty space with a point-like singularity at the center and an event horizon at the outer edge. It is so dense that no normal matter or radiation can escape its gravitational field, so that nothing - not even light - can ever escape (hence its blackness). It is thought that most galaxies have a supermassive black hole at their heart.

• Cosmic Microwave Background Radiation: Cosmic Microwave Background Radiation (CMB) is the “afterglow” of the Big Bang, a microwave radiation which still uniformly permeates all of space at a temperature of around -270°C (about 3° above absolute zero). It is considered to be the best evidence for the standard Big Bang model of the Universe.

• Cosmic Rays: High speed, energetic particles (about 90 per cent of which are protons) originating from space that impinges on Earth’s atmosphere. Some cosmic rays are generated by our own Sun, some by supernovas, some by as yet unknown events in the farthest reaches of the visible universe. The term “ray” is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles.

• Dark Matter: Matter that gives out no light and does not interact with the electromagnetic force, but whose presence can be inferred from gravitational effects on visible matter. It is estimated that there may be between 6 and 7 times as much dark matter as normal, bright matter in the Universe, although its exact nature remains a mystery.

• Light Year: A convenient unit for measuring the large distances in the Universe. It is the distance that light travels in one year which, given that light travels at 300,000 kilometers per second, works out to about 9,460,000,000,000 kilometers (9.46 trillion kilometers).

• Neutron Star: A star that has shrunk under its own gravity during a supernova event, so that most of its material has been compressed into neutrons only (the protons and electrons have been crushed together until they merge, leaving only neutrons). Neutron stars are very hot, quite small (typically 20 to 30 kilometers in diameter), extremely dense, have a very high surface gravity and rotate very fast. A pulsar is a kind of highly-magnetized rapidly-rotating neutron star.

• Supernova: A cataclysmic explosion caused by the collapse of an old massive star which has used up all its fuel. For a short time, such an explosion may outshine an entire galaxy of a hundred billion ordinary stars. It leaves behind a cloud of brightly colored gas called a nebula, and sometimes a highly compressed neutron star or even a black hole.

• Aurora Australis or Southern Lights are dynamic displays of light that appear in the Antarctic Skies in winter. They are nature’s light show. It is the name given to light emitted by atoms, molecules, and ions that have been excited by energetic charged particles. Common colors are pale green and pink in spiral curtains, arcs and streamers.

• Aurora Borealis also know as Northern Polar lights are natural occurring light display in the heavens in the Northern hemisphere. They are nature’s light show. It is the name given to light emitted by atoms, molecules, and ions that have been excited by energetic charged particles. Common colors are pale green and pink in spiral curtains, arcs and streamers.

• Binary Star is a star system composed of two stars that orbit a common center. The primary star is brightest; the secondary is referred to as the companion star.

• Heliopause – The point at which the solar wind meets the interstellar medium or solar wind from other stars

• International Space Station – A global cooperative program between the United States, Russia, Canada, Japan, and Europe, for the joint development, operation, and utilization of a permanently habitat in space close to low-Earth orbit.

• Kuiper Belt – a region in the outer Solar System beyond Neptune’s orbit that contains billions of small, icy bodies; Pluto is the largest known Kuiper Belt Object.

• Meteor – A flash of light that occurs when a meteoroid burns up in Earth’s atmosphere, also known as shooting star.

• Meteor Showers – Period of meteor activity that occurs when Earth collides with many meteoroids; an individual shower happens at the same time each year and has all its meteors appearing to radiate from a common point.

• Meteorite – Rock from space that survives as it passes through the Earth’s atmosphere and falls to the ground.

• Meteoroid – Small rock that orbits the Sun.• Nebula – a cloud of interstellar gas and dust; some nebulae

represent stellar nurseries, others represent stellar graveyards.• Red Dwarf – Smaller star with a low mass, cooler, and less

luminous than the Sun.• Red Giant – Cool star nearing the end of its cycle. These have

expanded up a hundred times the diameter of the Sun.• Van Allen Belts – Dual belts of charged particles from a solar

wind trapped in earth’s magnetic field above the atmosphere. Radiation zone of charged particles surrounding Earth. Shape of Van Allen belts is determined by Earth’s magnetic field.

• Redshift: A shift in the lines of an object’s spectrum toward the red end. Redshift indicates that an object is moving away from the observer. The larger the redshift, the faster the object is moving.

• Pulsar: Pulsars belong to a family of objects called neutron stars that form when a star more massive than the Sun runs out of fuel in its core and collapses in on itself. This creates a massive explosion called as a supernova.

7 The Universe

Self–Evaluation Test1. Which of the following will be studied by NASA’s Juno

mission launched in 2011?1. Evolution of Jupiter along with a study of its core2. Presence of water in its atmosphere3. Formation of the Magnetosphere

Which of the above statements is/are correct?(a) 1 and 2 (b) 2 and 3(c) 1 and 3 (d) All of the above

2. The phenomena of Red Shift is related to which of the following?(a) Expansion of Universe(b) Sea-floor spreading(c) Dispersion of light(d) Evolution of life

3. Consider the following statements with regard to asteroids:1. Asteroids are a swarm of small bodies in between Jupiter

and Mars that revolve around the Sun.2. They are considered to be the pieces of a planet which

probably exploded after its birth.

Which of the above statements is/are correct?(a) 1 only (b) 2 only(c) Both 1 and 2 (d) Neither 1 nor 2

4. Which of the following statements is/are true about Solar flares?1. These cause auroras at the poles when it interacts with

Earth’s atmosphere.2. Solar flares are able to disrupt communications satellites,

GPS and power grids.3. Large solar bursts have energies equivalent to one

billion hydrogen bombs. Select the correct answer using the codes given below:

(a) 1 only (b) 1 and 3 only(c) 2 and 3 only (d) All of the above

5. Which of the following statements is/are correct?1. The atmosphere of Mars is about 100 times thinner than

Earth’s.2. The Martian atmosphere contains methane.

Select the correct answer using the codes given below:(a) 1 only (b) 2 only(c) Both 1 and 2 (d) Neither 1 nor 2

ANSWERS

1. (d) 2. (a) 3. (c) 4. (d) 5. (c)

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