General astronomy

General astronomy

Contributors in General 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 ...