Saturday, August 28, 2010

FACTS ABOUT EARTH

1. Earth is third planet from Sun. It was formed 4.54 billion years ago.
2. Earth is Fifth Largest Planet.The order from largest to smallest planets is : Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury3. Earth is largest of the terrestrial planets in the Solar System in terms of diameter, mass and density.
What is a terrestrial Planet: A terrestrial planet is a planet that is primarily composed of silicate rocks. Mercury, Venus, Earth and Mars are terrestrial planets in Solar System.
Gas giants: They might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Jupiter, Saturn, Uranus & Neptune are Gas Giants.4. Earth’s orbit is 14, 96, 00,000 Kms.
5. Earth’s name is only one which is not derived from Greek mythology.
6. Due to Moon’s gravity and interaction with earth, the Earth’s rotation slows down by 2 milli seconds per century.7. There is one natural satellite Moon, however earth has some complex orbital relationship with Asteroids 3753 Cruithne and 2002 AA29.
3753 Cruithne is an asteroid in orbit around the Sun in 1:1 orbital resonance with that of the Earth. It is a periodic inclusion planetoid orbiting the Sun in an apparent horseshoe orbit.It has been called "Earth's second moon", although it is only a quasi-satellite.
Asteroid 2002 AA29 is a near-Earth asteroid discovered in January 2002. The asteroid spends most of its time following a "horseshoe orbit" that takes it near the Earth every 95 years as it follows Earth's orbit around the Sun. In about 600 years, it will appear to circle Earth in a quasi-satellite orbit.
8. Earth’s equatorial diameter is 12,756 kms, while Polar Diameter is 12,714 Kms. Equatorial circumference is 40077 kms while Polar Circumference is 40009 kms. Total surface area of earth is 510 million square kilometers, out of which 29% is covered by land and 71 % by water.
9. Earth is an oblate spheroid with 18-meter rise at the North Pole and 26 meter depression at the South Pole.10. Circumnavigation of the earth was the done for the first time by Ferdinand Magellan, who was a Portuguese explorer. 11. Earth’s mass is 5.9736×1024 Kg. Mean density is 5.517.
12. Highest land Point is Mount Everest 8848 meters, while lowest land Point is Dead Sea -397 meters.
13. Mean Ocean depth is 3730 meters and deepest ocean trench is 11022 meters Mariana Trench.
The Mariana Trench is the deepest part of the world's oceans, and the deepest location on the surface of the Earth's crust. It has a maximum depth of about 10,924 meters and is located in the western North Pacific Ocean, to the east and south of the Mariana Islands, near Guam.14. Earth’s mean surface temperature is 14 degree Celsius.
15. Earth's rotation period relative to the Sun (its mean solar day) is 86,400 seconds of mean solar time. Each of these seconds is slightly longer than an SI second because Earth's solar day is now slightly longer than it was during the 19th century due to tidal acceleration. Jean Bernard Leon Foucault was the first person who devised a public demonstration about earth’s rotation.
16. Rotation: Earth’s Period of rotation on Polar Axis is 23 hrs. 56 minutes 4.09 seconds. It is also called a Solar Day. Direction of Rotation is from West to East. The rotational velocity at the equator is 1667 kms per hours which decreases while progressing towards Poles and become zero at poles.
17. Revolution: Earth’s sidereal period or the time taken in completing one orbit around Sun is 365.25636 days. Its orbital speed is 29.8 km/s per second. Eccentricity of the orbit due to revolution is 0.0167. The one circuit which is about 365 days, 48 minutes and 45.68 seconds is called a tropical year. For convenience in calendars every fourth year is made a ‘leap year’ with 366 days.
18. Maximum distance of earth from Sun is 152.10 Million Kms at Aphelion , which is in the first week of July (July 2-5) )
19. Minimum Distance of earth from Sun is 147.10 kms at Perihelion (January 2-5)
20. Earth’s escape velocity is 11200 kms per second.
Escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy; i.e. the speed needed to "break free" from a gravitational field (without any additional impulse) and is theoretical, totally neglecting atmospheric friction.
21. Motions: There are five types of motions earth has:
1. Moves with Milky way as the entire galaxy travels through the universe
2. Follows the Sun which moves through Milky Way
3. Precession Movement which is like spinning top.
4. Revolution around Sun
5. Rotation on its Axis.
Escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy; i.e. the speed needed to "break free" from a gravitational field (without any additional impulse) and is theoretical, totally neglecting atmospheric friction.
22. While revolving around the Sun and rotating on its axis earth maintains a constant angle of 23.5 degree away from the perpendicular to the plane of the elliptic. Thus the inclined axis keeps a constant angle of 66.5 degree with reference to the plane of the elliptic.

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