70 relations: Abstraction, Apparent place, Aristotle, Astronomer, Astronomical Almanac, Astronomical object, Astronomy, Celestial, Celestial coordinate system, Celestial equator, Celestial pole, Celestial spheres, Centre (geometry), Classical planet, Concentric objects, Declination, Diurnal motion, Earth, Earth's orbit, Earth's rotation, Eclipse, Ecliptic, Ecliptic coordinate system, Equator, Equatorial coordinate system, Equidistant, Farnese Atlas, Firmament, Fixed stars, Galactic coordinate system, Geocentric coordinates, Geocentric model, Geometry, Great circle, Heliocentrism, Hellenistic period, History of astronomy, Infinity, Latitude, Line (geometry), Longitude, Millimetre, Moon, National Geospatial-Intelligence Agency, Navigation, Orbital plane (astronomy), Parallax, Parallel (geometry), Perspective (graphical), Plane (geometry), ..., Plane of reference, Plato, Point (geometry), Projection screen, Projective geometry, Proper motion, Ptolemy, Radius, Relative direction, Right ascension, Schiffer Publishing, Shorthand, Sky, Solar System, Sphere, Spherical astronomy, Stellar parallax, Terrestrial Time, Vanishing point, W. W. Norton & Company. Expand index (20 more) »

## Abstraction

Abstraction in its main sense is a conceptual process where general rules and concepts are derived from the usage and classification of specific examples, literal ("real" or "concrete") signifiers, first principles, or other methods.

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## Apparent place

The apparent place of an object is its position in space as seen by an observer.

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## Aristotle

Aristotle (Ἀριστοτέλης Aristotélēs,; 384–322 BC) was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidiki, in the north of Classical Greece.

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## Astronomer

An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside the scope of Earth.

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## Astronomical Almanac

The Astronomical AlmanacThe Astronomical Almanac for the Year 2015, (United States Naval Observatory/Nautical Almanac Office, 2014).

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## Astronomical object

An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.

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## Astronomy

Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

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## Celestial

Celestial may refer to.

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## Celestial coordinate system

In astronomy, a celestial coordinate system is a system for specifying positions of celestial objects: satellites, planets, stars, galaxies, and so on.

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## Celestial equator

The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.

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## Celestial pole

The north and south celestial poles are the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the celestial sphere.

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## Celestial spheres

The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others.

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## Centre (geometry)

In geometry, a centre (or center) (from Greek κέντρον) of an object is a point in some sense in the middle of the object.

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## Classical planet

In classical antiquity, the seven classical planets are the seven non-fixed astronomical objects in the sky visible to the naked eye: Mars, Jupiter, Venus, Saturn, Mercury, the Sun, and the Moon.

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## Concentric objects

In geometry, two or more objects are said to be concentric, coaxal, or coaxial when they share the same center or axis.

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## Declination

In astronomy, declination (abbreviated dec; symbol δ) is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle.

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## Diurnal motion

Diurnal motion (lit, from dies, lit. "day") is an astronomical term referring to the apparent daily motion of stars around Earth, or more precisely around the two celestial poles.

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## Earth

Earth is the third planet from the Sun and the only astronomical object known to harbor life.

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## Earth's orbit

Earth's orbit is the trajectory along which Earth travels around the Sun.

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## Earth's rotation

Earth's rotation is the rotation of Planet Earth around its own axis.

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## Eclipse

An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.

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## Ecliptic

The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.

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## Ecliptic coordinate system

The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions and orbits of Solar System objects.

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## Equator

An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).

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## Equatorial coordinate system

The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects.

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## Equidistant

A point is said to be equidistant from a set of objects if the distances between that point and each object in the set are equal.

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## Farnese Atlas

The Farnese Atlas is a 2nd-century Roman marble copy of a Hellenistic sculpture of Atlas kneeling with the celestial spheres, not a globe, weighing heavily on his shoulders.

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## Firmament

In Biblical cosmology, the firmament is the structure above the atmosphere of Earth, conceived as a vast solid dome.

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## Fixed stars

The fixed stars (stellae fixae) comprise the background of astronomical objects that appear to not move relative to each other in the night sky compared to the foreground of Solar System objects that do.

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## Galactic coordinate system

The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north.

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## Geocentric coordinates

Geocentric coordinates are an Earth-centered system of locating astronomical objects in the Solar System in three dimensions along the Cartesian X, Y, and Z axes.

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## Geocentric model

In astronomy, the geocentric model (also known as geocentrism, or the Ptolemaic system) is a superseded description of the universe with Earth at the center.

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## Geometry

Geometry (from the γεωμετρία; geo- "earth", -metron "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.

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## Great circle

A great circle, also known as an orthodrome, of a sphere is the intersection of the sphere and a plane that passes through the center point of the sphere.

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## Heliocentrism

Heliocentrism is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System.

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## Hellenistic period

The Hellenistic period covers the period of Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire as signified by the Battle of Actium in 31 BC and the subsequent conquest of Ptolemaic Egypt the following year.

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## History of astronomy

Astronomy is the oldest of the natural sciences, dating back to antiquity, with its origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory: vestiges of these are still found in astrology, a discipline long interwoven with public and governmental astronomy, and not completely disentangled from it until a few centuries ago in the Western World (see astrology and astronomy).

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## Infinity

Infinity (symbol) is a concept describing something without any bound or larger than any natural number.

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## Latitude

In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface.

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## Line (geometry)

The notion of line or straight line was introduced by ancient mathematicians to represent straight objects (i.e., having no curvature) with negligible width and depth.

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## Longitude

Longitude, is a geographic coordinate that specifies the east-west position of a point on the Earth's surface.

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## Millimetre

The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length.

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## Moon

The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.

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## National Geospatial-Intelligence Agency

The National Geospatial-Intelligence Agency (NGA) is both a combat support agency under the United States Department of Defense and an intelligence agency of the United States Intelligence Community, with the primary mission of collecting, analyzing, and distributing geospatial intelligence (GEOINT) in support of national security.

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## Navigation

Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.

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## Orbital plane (astronomy)

The orbital plane of a revolving body is the geometric plane on which its orbit lies.

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## Parallax

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.

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## Parallel (geometry)

In geometry, parallel lines are lines in a plane which do not meet; that is, two lines in a plane that do not intersect or touch each other at any point are said to be parallel.

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## Perspective (graphical)

Perspective (from perspicere "to see through") in the graphic arts is an approximate representation, generally on a flat surface (such as paper), of an image as it is seen by the eye.

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## Plane (geometry)

In mathematics, a plane is a flat, two-dimensional surface that extends infinitely far.

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## Plane of reference

In celestial mechanics, the plane of reference (or reference plane) is the plane used to define orbital elements (positions).

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## Plato

Plato (Πλάτων Plátōn, in Classical Attic; 428/427 or 424/423 – 348/347 BC) was a philosopher in Classical Greece and the founder of the Academy in Athens, the first institution of higher learning in the Western world.

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## Point (geometry)

In modern mathematics, a point refers usually to an element of some set called a space.

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## Projection screen

A projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience.

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## Projective geometry

Projective geometry is a topic in mathematics.

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## Proper motion

Proper motion is the astronomical measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars.

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## Ptolemy

Claudius Ptolemy (Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos; Claudius Ptolemaeus) was a Greco-Roman mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology.

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## Radius

In classical geometry, a radius of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length.

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## Relative direction

The most common relative directions are left, right, forward(s), backward(s), up, and down.

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## Right ascension

Right ascension (abbreviated RA; symbol) is the angular distance measured only eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point above the earth in question.

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## Schiffer Publishing

Schiffer Publishing Ltd. (also known as Schiffer Military History) is a family-owned publisher of nonfiction books.

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## Shorthand

Shorthand is an abbreviated symbolic writing method that increases speed and brevity of writing as compared to longhand, a more common method of writing a language.

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## Sky

The sky (or celestial dome) is everything that lies above the surface of the Earth, including the atmosphere and outer space.

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## Solar System

The Solar SystemCapitalization of the name varies.

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## Sphere

A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space that is the surface of a completely round ball (viz., analogous to the circular objects in two dimensions, where a "circle" circumscribes its "disk").

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## Spherical astronomy

Spherical astronomy or positional astronomy is the branch of astronomy that is used to determine the location of objects on the celestial sphere, as seen at a particular date, time, and location on Earth.

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## Stellar parallax

Stellar parallax is the apparent shift of position of any nearby star (or other object) against the background of distant objects.

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## Terrestrial Time

Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth.

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## Vanishing point

A vanishing point is a point on the image plane of a perspective drawing where the two-dimensional perspective projections (or drawings) of mutually parallel lines in three-dimensional space appear to converge.

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## W. W. Norton & Company

W.

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## Redirects here:

Astronomical map, Celestial Sphere, Celestial dome, Celestial hemisphere.

## References

[1] https://en.wikipedia.org/wiki/Celestial_sphere