Instruments {astrolabe}| can measure time by bright-star positions.
Instruments {equatorial armillary} can plot planet and star declinations and right ascensions and so measure time (Tycho Brahe).
Telescope mountings {equatorial mounting} can rotate around Earth axis to measure right ascension and rotate around axis {declination axis} perpendicular to Earth axis to measure declination.
Instruments {Foucault pendulum} can demonstrate that Earth rotates.
Instruments {orrery} can be mechanical solar-system models, showing planets rotating around Sun.
Instruments {plinth}| can use block to measure Sun-elevation angle at noon.
Instruments {quadrant, instrument} can measure star elevation.
Telescopes and micrometers can have line arrays {reticule}.
Instruments {Ptolemy's rules} {triquetrum} can measure star elevation angle as star crosses meridian.
Telescopes {Cassegrain reflector telescope} can use main mirrors to reflect to small mirrors and back through hole in main mirror.
Telescopes {Coudé system} can observe bright objects using objective mirrors that send light to concave mirrors that send light to flat rotatable mirrors and eyepieces, along mounting axis parallel to Earth axis.
Telescopes {reflecting telescope} can observe visible stars using parabolic mirrors as objectives.
Telescopes {refracting telescope} can observe stars using biconvex objective lens.
Telescopes {Schmidt telescope} can be wide-field refracting telescopes with lenses to correct for spherical aberration.
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Date Modified: 2022.0225