The planet on which we live.
The fragmental material composing part of the surface of the globe especially cultivable soil.
The Earth is an oblate spheroid. It is almost spherical flattened a little at the poles with a slight bulge at the centre equator.
Perihelion Nearest position of the Earth to the Sun.
Aphelion Farthest position of the Earth from Sun.
The Earth’s interior is composed of three major layers the crust the mantle and the core.
SIAL (silicon Aluminium) Upper part of the crust.
SIMA (silicon Magnesium) Lower part of the crust.
NIFE (Nickel Iron) outer part of the core.
Rotation of the Earth Earth spins on its imaginary axis from West to East in one day. Result causation of day and night, tides.
Revolution of the Earth Earth’s motion in elliptical orbit around the Sun in one year. Result change of seasons.
Statistical Data of the Earth
Age 4550 million years
Mass 5.976×10 kg
Mean Density 5.518 kg/it
Total surface Area 510 million sq km
Land Area 29.2% of the total surface area
Water Area 70.8% of the total surface area
Rotation speed 23 hr, 56 min and 4.100 sec
Revolution Speed 365 days, 5 hr and 45.51 sec
Dates when days and nights are equal March 21(Vernal Equinox) 23 September(Autumnal Equinox)
Longest day 21st June (summer solstice) Sun is vertically overhead at tropic of cancer
Longest night 22nd December (winter solstice) Sun is vertically overhead at tropic of Capricorn
Escape velocity 11.2 km/sec
Mean surface temperature 15°C
Distance North or South of the equator measured in degrees up to 90 degrees.
Located at a latitude of 40 degrees North.
First use, 14th century.
Imaginary lines drawn on the Earth’s surface parallel to the equator. Equator is the biggest latitude that divides Earth in two equal hemispheres (North and south).
Tropic of cancer 23.5°N
Tropic of Capricorn 23.5°S
Arctic circle 66.5°N
Antarctic circle 66.5°S
- Each degree of latitude equals 111 km.
- The most important line of latitude is the Equator.
Distance measured in degrees East or West from on imaginary line ( called the prime meridian) that goes from the North pole to the South pole and that passes through greenwich England.
An imaginary line that circles the Earth at a particular longitude.
- Meridians are a series of semicircles that run from pole to pole passing through the equator.
- Prime Meridian passes through Greenwich near London, divides the Earth in Eastern and western hemisphere. Its value is 0°.
- Longitude has very important function it determines local time in relation to Greenwich Mean Time (GMT).
International Date Line
It is the longitudinal line at 180° East or 180° West meridian, which when crossed, the date changes by exactly one day.
Indian Standard Time
- The Earth takes approximately 24 hours to complete one r. It takes 24 hours to complete 360° of its rotation.
- 1° change of longitude corresponds to 4 minutes difference in time. Towards East-addition Towards West-subtraction.
- Indian Standard Time is calculated on the basis of 82.5°E longitude which passes through Uttar Pradesh, Madhya Pradesh, Odisha, Chattisgarh and Andhra Pradesh.
- IST is 5 hr 30 min ahead of GMT.
When the light of the Sun or the moon is blocked by another body, the Sun or the Moon is said to be in eclipse.
Solar Eclipse it is caused when the Moon revolving around the Earth comes in between the Earth and the Sun, thus making a part or whole of the Sun invisible from a particular part of the Earth. Thus the eclipse can be partial or complete.
Lunar Eclipse when the Earth comes between the Moon and the Sun, the shadow cast by the Earth on the Moon results in a lunar eclipse.
Rocks are made up of individual substances, called minerals, found mostly in solid state. Rocks are classified into three major types
Igneous Rocks are formed by the solidification of the molten magma, Mica, Granite.
Sedimentary Rocks are formed due to accumulation of rock particles and organic matter in layers, under tremendous pressure, Gravel, Peat, Gypsum.
Metamorphic Rocks These rock were originally igneous or sedimentary but later changed due to pressure, heat or action of water Gneiss, Marble, Quartzite etc.
Types of Rock
State, Mica Schist
A shaking of a Part of the Earth’s surface that often causes great damage.
- Any sudden disturbance below the Earths surface may produce vibrations or shaking in Earth’s crust and some of these vibrations, when reach the surface, are known as earthquakes.
- The intensity of earthquake waves is recorded by seismograph.
- Focus is the point beneath the Earth where earthquake originates.
- Epicentre is the point just above the focus on the Earth’s surface.
Volcanism is the phenomenon of sudden eruption of hot magma, gases, Ash and other material from inside the Earth to its surface.
Types of Volcanoes
Active which erupts frequently Mauna Loa (Hawaii), Etna (Sicily), Vesuvius (Italy), Stromboli (Mediterranean Sea).
Dormant Not erupted for quite some time, Fujiyama (Japan), Krakatoa (Indonesia), Barren Island (Andamans).
Extinct Not erupted for several centuries, Arthur’s seat, Edinburgh, Scotland.
Ring of Fire Hundreds of active volcanoes found on the land near the edges of the pacific ocean.
Tsunami Large ocean wave that is caused by sudden motion on the ocean floor. Motion could be an earthquake, volcanic eruptions or underwater landslide.
A Natural feature (such as a mountain or valley) of the Earth’s surface.
There are three major landforms mountains, plateaus and plains.
An uplifted portion of the Earth’s surface is called a hill or a mountain. Mountains are classified into following four types
Fold Mountains are formed by folding of crustal rocks by compressive forces. Himalayas (Asia), Alps (Europe).
Block Mountains when great blocks of the Earth’s crust are raised or lowered during the last stage of mountain building, block mountains are formed, Vosges in France, Black Forest mountains in Germany.
Volcanic Mountains These are formed by the matter thrown out from the volcanoes, and are also known as mountains of accumulation, Mt Mauna Loa in Hawaii, Mt Popa in Myanmar.
Residual or Dissected Mountains They are known as relict mountains or mountains of circum-denudation. They owe their present form to erosion by different agencies, Nilgiris, Girnar and Rajmahal.
Plateaus are flat, table like, Upland areas with rough top surface and steep side walls.
A relatively low-lying and flat land surface with least difference between its highest and lowest points is called a plain.
The air in a particular place or area.
The whole mass of air that surrounds the earth.
The vast expanse of air, which envelops the Earth all around is called the atmosphere. It extends to thousands of kilometres.
It protects the Earth’s surface from the Sun’s harmful, ultraviolet rays.
Structure of Atmosphere
Layer Height (km)
Troposphere 0-18 km
Stratosphere 18-50 km
Mesosphere 50-80 km
Lonosphere 80-400 km
Exosphere Above 400 km
- Contains 75% of the gases in the atmosphere. As height increases, temperature decreases (about 6.5°C per 1 km ascent).
- This layer contains the ozone layer. The temperature remains fairly constant. At upper layer temperature is almost 0°C
- This is the coldest region of the atmosphere. The temperature drops to about-100°C.
- Radio waves are bounced off the ions and reflect waves back to the Earth. This generally helps radio communication.
- Upper part of exosphere is called Magnetosphere. The temperature keeps on rising constantly at high rate.