General astronomy

General astronomy

Industry: Astronomy

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General astronomy

spectral type

Astronomy; General astronomy

(also spectral class) the classification of a star according to its temperature as measured from the strengths of its spectral lines. In order of temperatures from hottest to coolest the spectral ...

spectroscopic binary

Astronomy; General astronomy

two stars orbiting a common point at too great a distance away from us to resolve the two stars individually, but whose binary nature is indicated in the periodic shift of their spectral lines as ...

a method of determining distances to stars from knowledge of the luminosity of their spectral types and measurement of their apparent brightness. The distances are derived from the inverse square law ...

spherical aberration

Astronomy; General astronomy

a defect seen in images that is caused by the objective not being exactly shaped (e.g., an objective mirror not being exactly parabolic) so that not all of the light is focussed to the same point.

spiral galaxy

Astronomy; General astronomy

a highly flattened galaxy with a disk and a central bulge. The disk has a spiral pattern with slightly more stars and gas than in the rest of the disk. A slow, steady star formation rate means that ...

spring tide

Astronomy; General astronomy

tide that has a large change between low and high tide. It occurs at new and full phase, when the Moon's tidal effect is aligned with the Sun's tidal effect.