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| | The '''Earth''' is the only known planet in our '''Solar System''' which can support life. It contains water, reasonable levels of oxygen, and a stable temperature range. Geometrically speaking, Earth is the largest of the terrestrial (rocky) planets in the solar system. | | The '''Earth''' is the only known planet in our '''Solar System''' which can support life. It contains water, reasonable levels of oxygen, and a stable temperature range. Geometrically speaking, Earth is the largest of the terrestrial (rocky) planets in the solar system. |
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| | + | ==Physical Description== |
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| | + | Within the [[solar system]], Earth is the third planet from the Sun. It is approximately 8,000 miles (13,000 km) in diameter, which means that its equatorial circumference (measured around the equator) is 24,901 miles (40,075 kilometers), and the polar circumference is slightly less at 24,809 miles (40,008 km).<ref>http://geography.about.com/library/faq/blqzcircumference.htm</ref> The reason its metric circumference is so close to the "round number" of 40,000 is that the [[kilometer]] was defined (by the French) as 1/10,000th the distance from the equator to the [[North Pole]]. |
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| | + | Its surface area is approximately 4·π (4000 mi)<sup>2</sup> = 200 million square miles (510 million km<sup>2</sup>). It has been said that Earth should really be called "water", as the larger part of it—about 70%—is covered by water. In fact, the Pacific and Indian oceans alone cover about half of the Earth's surface. |
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| | + | The Earth orbits at an average distance of about 93 million miles (150 million km) from the Sun in an almost circular orbit. It takes light (and other forms of electromagnetic radiation) approximately 500 seconds to travel from the Sun to the Earth, i.e. the distance can also be stated as "500 light-seconds." The distance to nearby stars is made by measuring the stellar [[parallax]] between observations when the earth is at opposite ends of its orbit, so the earth's orbit itself is a measuring stick for astronomical distances, and is known as the ''astronomical unit'' (A. U.) It is worth noting that if the Earth were slightly closer to the Sun, it would be too hot for life (just as Venus is) while if Earth were slightly further away from the Sun, water would freeze and life would be impossible. |
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| | + | ==Origin== |
| | People disagree about when and how the Earth was created. The three most popular ideas are: | | People disagree about when and how the Earth was created. The three most popular ideas are: |
| | #That God created the Earth several hundred generations ago, as recounted in [[Genesis]]. By adding years and other time indications in the [[Old Testament]] chronologies, one can calculate the age of the Earth as approximately 6,000 years (see [[Date of creation]] and [[Young Earth Creationism]]). | | #That God created the Earth several hundred generations ago, as recounted in [[Genesis]]. By adding years and other time indications in the [[Old Testament]] chronologies, one can calculate the age of the Earth as approximately 6,000 years (see [[Date of creation]] and [[Young Earth Creationism]]). |
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| | Clashes between adherents of these ideas have gone on since time immemorial (see [[origins debate]]), though the last theory has only been fully developed in the last 200 years. | | Clashes between adherents of these ideas have gone on since time immemorial (see [[origins debate]]), though the last theory has only been fully developed in the last 200 years. |
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| − | ==Physical Description==
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| − | Within the [[solar system]], Earth is the third planet from the Sun. It is approximately 8,000 miles (13,000 km) in diameter, which means that its equatorial circumference (measured around the equator) is 24,901 miles (40,075 kilometers), and the polar circumference is slightly less at 24,809 miles (40,008 km).<ref>http://geography.about.com/library/faq/blqzcircumference.htm</ref> The reason its metric circumference is so close to the "round number" of 40,000 is that the [[kilometer]] was defined (by the French) as 1/10,000th the distance from the equator to the [[North Pole]].
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| − | Its surface area is approximately 4·π (4000 mi)<sup>2</sup> = 200 million square miles (510 million km<sup>2</sup>). It has been said that Earth should really be called "water", as the larger part of it—about 70%—is covered by water. In fact, the Pacific and Indian oceans alone cover about half of the Earth's surface.
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| − | The Earth orbits at an average distance of about 93 million miles (150 million km) from the Sun in an almost circular orbit. It takes light (and other forms of electromagnetic radiation) approximately 500 seconds to travel from the Sun to the Earth, i.e. the distance can also be stated as "500 light-seconds." The distance to nearby stars is made by measuring the stellar [[parallax]] between observations when the earth is at opposite ends of its orbit, so the earth's orbit itself is a measuring stick for astronomical distances, and is known as the ''astronomical unit'' (A. U.) It is worth noting that if the Earth were slightly closer to the Sun, it would be too hot for life (just as Venus is) while if Earth were slightly further away from the Sun, water would freeze and life would be impossible.
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| | == Young Earth Creationist view == | | == Young Earth Creationist view == |
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| | ===Shape of the Earth=== | | ===Shape of the Earth=== |
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| − | Some Young Earth Creationists and Biblical literalists also dispute the shape of the earth, saying that according to the Bible, the earth is flat rather than spherical (presumably square, given that it is described as having "four corners" (Revelations 7:1)). However, no credible organization has ever expressed support for this theory.<ref>http://www.lhup.edu/~dsimanek/crea-fe.htm</ref> Some Biblical literalists also dispute the idea that the earth rotates around the sun.<ref>http://www.lhup.edu/~dsimanek/febible.htm</ref> | + | Some people dispute the shape of the earth, saying that according to the Bible, the earth is flat rather than spherical (presumably square, given that it is described as having "four corners" (Revelations 7:1)). However, no credible organization has ever expressed support for this theory.<ref>http://www.lhup.edu/~dsimanek/crea-fe.htm</ref> Some have disputed the idea that the earth rotates around the sun.<ref>http://www.lhup.edu/~dsimanek/febible.htm</ref> |
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| | In Revelations 7:1 it is stated: | | In Revelations 7:1 it is stated: |