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Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. [10] Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv).
Despite the trapping of 40 Ar in many rocks, it can be released by melting, grinding, and diffusion. Almost all argon in the Earth's atmosphere is the product of 40 K decay, since 99.6% of Earth's atmospheric argon is 40 Ar, whereas in the Sun and presumably in primordial star-forming clouds, argon consists of < 15% 38 Ar and mostly (85%) 36 Ar.
It is mainly located in the lower portion of the stratosphere from about 15–35 km (9.3–21.7 mi; 49,000–115,000 ft), though the thickness varies seasonally and geographically. About 90% of the ozone in Earth's atmosphere is contained in the stratosphere. The ionosphere is a region of the atmosphere that is ionized by solar radiation.
Earth's atmosphere photographed from the International Space Station.The orange and green line of airglow is at roughly the altitude of the Kármán line. [1]The Kármán line (or von Kármán line / v ɒ n ˈ k ɑːr m ɑː n /) [2] is a conventional definition of the edge of space; it is widely but not universally accepted.
The Spitzer Space Telescope is in an Earth-trailing heliocentric orbit drifting away c. 0.1 AU per year. In c. 2013–15 it has passed L 5 in its orbit. Hayabusa2 passed near L 5 during the spring of 2017, and imaged the surrounding area to search for Earth trojans on 18 April 2018.
The asteroid, which contains the building blocks of life according to recent studies of samples returned to Earth by NASA’s OSIRIS-REx mission, is a medium-size space rock reaching about 1,640 ...
Two new studies from the asteroid Bennu reveal pre-biology deep in space. ... an airless, 1,614-ft. rubble pile orbiting the sun about 40.2 million miles from Earth. But that doesn’t mean that ...
The composition of Earth's atmosphere is determined by the by-products of the life that it sustains. Dry air (mixture of gases) from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally a variable amount of water vapor is ...