Astrometry

alt=Planispheric Astrolabe made of brass, cast, with fretwork rete and surface engraving|thumb|upright=1.2|North African, planispheric astrolabe. Khalili Collections|Khalili Collection. thumb|upright|A modern astrolabe made in 2013, in Tabriz, Iran.

thumb|upright=1.4|right|A simplified illustration of the parallax of an object against a distant background due to a perspective shift. When viewed from "Viewpoint A", the object appears to be in front of the blue square. When the viewpoint is changed to "Viewpoint B", the object appears to have moved in front of the red square. thumb|right|This animation is an example of parallax. As the viewpoint moves side to side, the objects in the distance appear to move more slowly than the objects close to the camera. In this case, the white cube in front appears to move faster than the green cube in t

thumb|360x360px|Using optical interferometry to determine precise positions of stars. Courtesy NASA/JPL-Caltech

branch of astronomy

American astronomer and human calculator (1868–1921)

In astronomy and celestial navigation, an ephemeris (; ; , ) is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices ar

type of variable star

phenomenon when two astronomical objects or spacecraft have the same right ascension or ecliptic longitude as observed from Earth

phenomenon when a celestial body passes directly between a larger body and the observer

situation where two celestial bodies are on opposite sides of the sky, viewed from a given place (usually Earth)

astronomical measure of the observed changes in the apparent places of stars in the sky

type of motion in astronomy. A component of the rotating motion of a planet under the influence of gravitational pull by moons, other planets or the central star

component of the velocity in radial direction

phenomenon in astronomy

angular measurement describing how large a sphere or circle appears from a given point of view

straight-line configuration of three celestial bodies in astronomy

branch of astronomy about the celestial sphere

astronomical catalogue that lists stars

succession of methods by which astronomers determine the distances to celestial objects

astronomical bodies that appear not to move relative to each other in the night sky

Astronomical instrument for timing of the passage of stars

scientific agency and observatory in Washington, D.C., United States

conjunction of planets Jupiter and Saturn

measure for how wide an angle is

the apparent motion of celestial objects around Earth due to the planet's rotation

thumb|Graphic reconstruction of the dioptra, by Venturi, in 1814. (An incorrect interpretation of Heron's description)

celestial reference system using reference celestial sources observed at radio wavelengths

network of 6 small automated telescopes, aiming to find and explore extrasolar planets and variable stars, maintained by the Harvard-Smithsonian Center for Astrophysics

apparent shift of position of a nearby star against the background of distant objects during Earth's orbital period

map of the Sky

astronomical instrument

medieval name for an ancient astronomical instrument

Type of hourglass used at sea

motion of Earth's rotational axis relative to its crust

type of variable star

thumb|The Moon and [[Venus in the evening sky on three consecutive days. The centre image shows an appulse between the two objects.]]

Soviet astronomer (1902-1992)

type of variable stars

type of variable star

position of an object in space as seen by an observer, which may differ from actual position due to geometric and physical effects

distance measure in astronomy using the period of variable stars to find their absolute brightness

astronomical observatory in Shanghai, China

thumb|Animation of free (or Euler) nutation of a sphere thumb|upright=0.6| in obliquity of a planet caused by the Gravity|gravitational forces of other nearby bodies acting upon the planet

astronomic or geodetic instrument which is directed exactly to the zenith

iterative technique to find the properties of the stars in a binary pair

astronomical object of well-known physical size, used to determine distance via trigonometry

the apparent angular position of any given star in the sky, which seems fixed onto an arbitrary sphere centered on Earth

interactive facility that computes the position of many solar system objects

technique in stellar astrophysics

transit of Venus across the Sun visible from Earth in 1639

estimation of orbits of objects

short-term changes in the length of the day

Procedure to determine asteroid masses

Celestial coordinate system

astronomical method for measuring the distances to stars

thumb|Fully Assembled Cosmolabe by Jacques Besson, 1566 thumb|right|Cosmolabe, 16th century thumb|Foot of a Cosmolabe by Jacques Besson, 1566

astronomical event

optical instrument used to measure angles