19 Terms
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General astronomy
Industry: Astronomy
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General astronomy
atomic mass unit (u, dalton)
Astronomy; General astronomy
The masses of atoms and molecules are generally given in atomic mass units. These units are based on a scale in which the mass of carbon 12 is taken to be 12. Atomic masses were originally given as ...
atomic number (charge number)
Astronomy; General astronomy
The number of protons in an atom's nucleus. This determines the type of element.
attenuation
Astronomy; General astronomy
The falling off of the energy density of radiation with distance from the source, or with passage through an absorbing or scattering medium.
aurora
Astronomy; General astronomy
the light produced by excited atoms and ions in the upper atmosphere of a planet
aurora australis
Astronomy; General astronomy
an aurora ocurring in the southern hemisphere of the Earth
aurora borealis
Astronomy; General astronomy
an aurora ocurring in the northern hemisphere of the Earth
autoionization
Astronomy; General astronomy
A phenomenon occurring when a discrete double-excitation state of an atom lies in the ground-state continuum. In the autoionization process one of the excited electrons is ejected, leaving the ion in ...
