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- Earth-
- Area – 510 million sq km.
- Perigee (nearest position of earth to moon) – 3,56,000 km.
- Apogee (farthest position of earth to moon) – 4,07,000 km.
- Aphelion (farthest position of earth from sun) on 4th July about 152 million km.
- Perihelion (nearest position of earth to sun) on 3rd jan about 147 million km.
- History of earth is studied in terms of geological years, periods and epochs.
- Earth is an oblate spheroid (bulges at the equator and flattened at the poles), also called geoid.
- At poles weight will be more.
- Geodesy is a branch of science which deals with measuring the earth’s size and shape.
- Equinoxes (sun is vertically overhead at the equator)-
- 21st march – vernal equinox.
- 23rd September – autumnal equinox.
- Age of earth – 4.5 to 4.6 billion years.
- Earth’s circumference at equator – 24901.55 miles (40075.16 km).
- Earth’s circumference between the poles – 24859.82 miles (40008 km).
- Earth’s diameter at the equator – 7926.28 miles (12756.1 km).
- Lowest elevation on land – dead sea 1369 ft (417.27 m) below sea level.
- Deepest point in the earth – mariana trench in western Pacific Ocean (10994 m).
- Highest temperature recorded – 134.0 0 F in death valley, California (USA) on 10th july,1913.
- Lowest temperature recorded – 128.5 0 F in vostok, Antarctica on 21st july,1983.
- 21st June (summer solstice)-
- Longest day in northern hemisphere.
- Shortest day in southern hemisphere.
- Sun is vertically overhead at the tropic of cancer.
- 22nd December (winter solstice)-
- Longest day in southern hemisphere.
- Shortest day in northern hemisphere.
- Sun is overhead at the tropic of capricorn.
- 21st march and 23rd September – equal day and night in both the hemispheres.
- Rotation of earth-
- It takes 23 hrs 56 min 40.91 sec (approx. 24 hrs).
- Speed is max at equator – 1667 km/h ; and min at poles – 0 km/h.
- At equator day and night are equal.
- Effect of rotation of earth-
- Causation of day and night.
- Change in direction of winds and ocean currents.
- Difference of 1 hour between the two meridians which are 15 0 apart.
- Division of day and night is considered by the circle of illumination.
- Revolution of the earth-
- It takes 365 days 5 hours 48 min 45.51 sec (approx. 365¼ days).
- Effect of revolution of the earth-
- Variation of length of day and night.
- Seasons-
- Spring: When the sun is directly overhead the equator (21st march).
- Summer: When the sun is directly overhead the tropic of cancer, the North Temperate Zone experiences summer (21st June).
- Autumn: When the sun returns to the equator, the North Temperate Zone experiences the season of autumn (23rd September).
- Winter: The sun is at the tropic of Capricorn, the North Temperate Zone experiences winter (22nd dec).
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