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The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).
In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. [20] The altitudes of the five layers are: Exosphere: 700 to 10,000 km (440 to 6,200 miles) [21] Thermosphere: 80 to 700 km (50 to 440 miles) [22]
For example, during the opposition of 17 December 2002, Saturn appeared at its brightest due to the favorable orientation of its rings relative to the Earth, [178] even though Saturn was closer to the Earth and Sun in late 2003. [178] From time to time, Saturn is occulted by the Moon (that is, the Moon covers up Saturn in the sky). As with all ...
Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 20% of Earth’s radius or 70% of the Moon's radius. [1] [2] There are no samples of Earth's core accessible for direct measurement, as there are for Earth's mantle. [3]
Most water in Earth's atmosphere and crust comes from saline seawater, while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Earth is saline or salt water, with an average salinity of 35‰ (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land.
As of 2015, a systematic review of 20 studies, of up to 15,521 men, who were measured by health professionals rather than themselves, concluded that the average length of an erect human penis is 13.12 cm (5.17 in), while the average circumference of an erect human penis is 11.66 cm (4.59 in). [2]
[10] [11] The answer depends on the definition of "people", i.e., whether only Homo sapiens are to be counted, or all of the genus Homo; due to the small population sizes in the Lower Paleolithic, however, the order of magnitude of the estimate is not affected by the choice of cut-off date substantially more than by the uncertainty of estimates ...
In the oceans, the K–Pg extinction killed off plesiosaurs and mosasaurs and devastated teleost fish, [27] sharks, mollusks (especially ammonites, which became extinct), and many species of plankton. It is estimated that 75% or more of all species on Earth vanished. [28]