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The mass attenuation coefficient (also called "mass extinction coefficient"), which is the absorption coefficient divided by density; The absorption cross section and scattering cross-section, related closely to the absorption and attenuation coefficients, respectively "Extinction" in astronomy, which is equivalent to the attenuation coefficient
Dresbachian extinction event: 502 Ma: End-Botomian extinction event: 517 Ma: Precambrian: End-Ediacaran extinction: 542 Ma: Anoxic event [45] Great Oxygenation Event: 2400 Ma: Rising oxygen levels in the atmosphere due to the development of photosynthesis as well as possible Snowball Earth event. (see: Huronian glaciation.)
The most famous of these mass extinction events — when an asteroid slammed into Earth 66 million years ago, dooming the dinosaurs and many other species — is also the most recent. But ...
Extinction coefficient refers to several different measures of the absorption of light in a medium: Attenuation coefficient , sometimes called "extinction coefficient" in meteorology or climatology Mass extinction coefficient , how strongly a substance absorbs light at a given wavelength, per mass density
Asteroid impacts: one large impact is associated with a mass extinction, that is, the Cretaceous–Paleogene extinction event; there have been many smaller impacts but they are not associated with significant extinctions, [105] or cannot be dated precisely enough.
A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H 2 O).
One classical thermal escape mechanism is Jeans escape, [1] named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. [2] In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy.
Strong extinction in Earth's atmosphere of some wavelength regions (such as X-ray, ultraviolet, and infrared) is overcome by the use of space-based observatories. Since blue light is much more strongly attenuated than red light, extinction causes objects to appear redder than expected; this phenomenon is called interstellar reddening. [5]