EARTH1 - EARTH AND ITS POPULATION The Earth The planet on...

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CVEN 3698 - Lecture Notes 2 Page 1 © B. Amadei EARTH AND ITS POPULATION The Earth The planet on which we live is only one of nine planetary bodies that revolve around the Sun in the solar system. Earth is the third in distance from the sun and the fifth largest of the planets in diameter. The Earth is essentially a nearly spherical geoid or ellipsoid of rotation slightly flattened at the poles. Some of its characteristics are listed in Table 1 and below: Diameter varies between 12,713.54 km or 7,899.83 mi (polar diameter) and 12,756.34 km or 7,926.42 mi (equatorial diameter); Volume is about 1,083 billion km 3 or 259 billion mi 3 ; Mass is about 5.98 x 10 21 metric tons; Total surface area is about 510 million km 2 or 197 million mi 2 , 71% of which is covered with water; Average density is 5.52 g/cm 3 which is about twice that of its surface rocks; Highest point is Mount Everest at 29,000 ft (8.848 km) and its deepest point is the Mariana trench (near the Philippine Island of Mindanao) at -36,500 ft (-11.033 km); Highest temperature is 58 ° C (136 ° F) at Al Aziziyah, Libya and lowest is -89.6 ° C (- 128.6 ° F) at Vostok Station, Antartica. The average surface temperature is 14 ° C (57 ° F); Atmospheric components: 78% nitrogen, 21% oxygen and 1% argon. Table 1. Earth statistics.
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CVEN 3698 - Lecture Notes 2 Page 2 © B. Amadei Additional information about the Earth and other planets can be found in the following web pages or by consulting various encyclopedias: / The Earth consists of five parts: the atmosphere (gaseous), the hydrosphere (liquid), and three solid parts called the lithosphere, the mantle and the core. The oldest rocks on Earth have been dated to be 4 billion years old. Using radioactive dating of rocks, scientists have been able to construct an absolute chronology of geologic time. The geologic time scale is the result (see Fig. 1). If the age of the Earth were reduced to a 24-hour scale, the human species would not appear until the last few seconds. We will talk about the geologic time scale later during the semester. For the time being, you should know that the Earth is old (but well alive) with an age of about 4.65 billion years (based on the age of meteorites that fell on Earth). The behavior of earthquake waves has led geophysicists to conclude that the Earth is a density- stratified planet consisting of: (1) a dense core (inner and outer), (2) a mantle (inner and outer), (3) and the crust . An idealized picture of the Earth is shown in Fig. 2. The core is about 3,486 km (2,178 miles) in radius and it is believed to consist of iron with a solid inner part and a liquid outer part. The density of the core ranges from 9.4 g/cm 3 at the outer limit to 13.7 g/cm 3 at the center of the core. The mantle is 2,885 km (1,803 miles) thick and is believed to consist of silicate rocks rich
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This note was uploaded on 02/26/2008 for the course CVEN 3698 taught by Professor Amadei during the Spring '08 term at Colorado.

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EARTH1 - EARTH AND ITS POPULATION The Earth The planet on...

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