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The value of Earth, i.e. the net worth of our planet, is a debated concept both in terms of the definition of value, as well as the scope of "Earth". Since most of the planet's substance is not available as a resource, "earth" has been equated with the sum of all ecosystem services as evaluated in ecosystem valuation or full-cost accounting. [1]
Aryabhata ( ISO: Āryabhaṭa) or Aryabhata I[ 3][ 4] (476–550 CE) [ 5][ 6] was the first of the major mathematician - astronomers from the classical age of Indian mathematics and Indian astronomy. His works include the Āryabhaṭīya (which mentions that in 3600 Kali Yuga, 499 CE, he was 23 years old) [ 7] and the Arya- siddhanta .
Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust.
The second book contains his calculation of the circumference of the Earth. This is where, according to Pliny, "The world was grasped." Here Eratosthenes described his famous story of the well in Syene, wherein at noon each summer solstice, the Sun's rays shone straight down into the city-center well. [22]
The Fall 1969 issue of the Whole Earth Catalog. The Whole Earth Catalog ( WEC) was an American counterculture magazine and product catalog published by Stewart Brand several times a year between 1968 and 1972, and occasionally thereafter, until 1998. The magazine featured essays and articles, but was primarily focused on product reviews.
In 1862, the physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and 400 million years. [19] [20] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface temperature gradient to decrease to its present value.
The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids. [54] The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km).
Earth's rotation. Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Polaris, Earth turns counterclockwise . The North Pole, also known as the Geographic North ...