Celestial Sphere
Related Category: Astronomy: General
imaginary sphere of infinite radius with the earth at its center. It is used for describing the positions and motions of stars and other objects.
Celestial Sphere
Used to describe the position of objects in the sky, the celestial sphere is a fictitious sphere centred on the Earth upon which all celestial bodies can be projected.
Celestial sphere
The celestial sphere is divided by the celestial equator.
celestial sphere
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The celestial spheres, or celestial orbs, were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, adopted by Aristotle and developed by Ptolemy, Copernicus and others.
The Celestial Sphere
It is useful in discussing objects in the sky to imagine them to be attached to a sphere surrounding the earth. This fictitious construction is called the celestial sphere.
The principal axis of the celestial sphere is aligned with the axis of rotation of the earth. The pole star, Polaris, is so called because it is the most resaonably bright star closest to this axis on the sky. There is no southern equivalent.
Celestial Sphere
When we look at the sky, it is difficult to tell how far the stars are. It seems that all the stars lie on a "flat" surface.
Celestial Sphere Defined
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Celestial sphere. An imaginary sphere of great (or infinite) radius that is centered on the earth and is used for practical purposes in astronomical observing.
celestial sphere Imaginary sphere surrounding the Earth, to which all objects in the sky were once considered to be attached.
celestial sphere: an imaginary sphere, arbitrarily large and co-centred with the Earth, on which all the stars appear to be fixed.
celestial sphere
the apparent sphere of the sky; an imaginary sphere of immense radius centered on Earth often used to plot the coordinates of objects in the sky
charge-coupled device ...
Celestial sphere Imaginary sphere of infinite size surrounding the Earth and to which celestial bodies seem to be attached.
Celestial sphere- the imaginary sphere enveloping the Earth upon which the stars, galaxies, and other celestial objects all appear to lie ...
Celestial Sphere - The three-dimensional sky seemingly projected onto the inside two-dimensional surface of an imaginary, infinite sphere surrounding the Earth. The Sun, Moon, Planets and stars appear to be located on this celestial sphere.
celestial sphere
The imaginary sphere on which the stars and deep sky objects lie. Although an inaccurate representation of the three dimensional universe, the celestial sphere is a useful way to represent the night sky.
Celestial Sphere The projection of space and the objects therein onto an imaginary sphere surrounding the Earth and centred on the observer.
Central Meridian The imaginary line through the poles of a planet that bisects the planetary disc.
Celestial sphere
an imaginary sphere centered on the earth on which all of the stars are imagined to be projected.
celestial sphere: An imaginary sphere of very large radius surrounding Earth and to which the planets, stars, sun, and moon seem to be attached.
center of mass: The balance point of a body or system of bodies.
Celestial sphere -- An immense sphere surrounding Earth, to which the fixed stars seen at night appear to be attached.
Celestial Sphere
An imaginary sphere of arbitrary radius upon which celestial bodies may be considered to be located. As circumstances require, the celestial sphere may be centered at the observer, at the Earth's center or at any other location.
The Celestial Sphere
A useful construct for describing locations of objects in the sky is the celestial sphere, which is considered to have an infinite radius.
THE CELESTIAL SPHERE
Over the course of a night, the constellations seem to move smoothly across the sky from east to west, ...
Celestial Sphere
An imaginary sphere encompassing the Earth that represents the sky. Astronomers chart the sky using the celestial coordinates of the sphere to locate objects in the cosmos.
celestial sphere - (n.)
The visible, seemingly spherical surface that appears to surround Earth and to be centered at the observer.
Celsius scale - (n.) ...
CELESTIAL SPHERE
The celestial sphere is an imaginary sphere whose center is the Earth. This sphere is used by astronomers to map celestial objects.
The celestial sphere: An imaginary sphere of very large radius centered on the observer or what we can refer to as the apparent sphere of the sky.
Objects on the celestial sphere, including RA and stars, will move across your meridian and some may pass in and out of your zenith. As time goes by any star at your zenith, and any RA line along your meridian, will move on.
A point on the celestial sphere lying in the constellation Hercules toward which the Sun and the solar system are moving with respect to the Local Standard of Rest at a rate of about 19.4 km per second (about 4.09 AU per year). [H76] ...
Even though the Celestial Sphere is not a real model of the sky, it is useful for mapping out locations of objects in the sky. The Celestial Sphere was set up so that it used some of the coordinates that are used on the Earth.
The point on the celestial sphere where the Sun crosses the Earth's equatorial plane from south to north. Also called the first point of Aries.
parallel of altitude A circle of the celestial sphere parallel to the horizon connecting all points of equal altitude. Also called altitude circle, almucantar. See circle of equal altitude.
celestial coordinates (NASA SP-7, 1965) Any set of coordinates used to define a point on the celestial sphere.
See also: Meteorite Path The projection of the line of motion of the meteor on the celestial sphere, as seen by the observer.
celestial sphere
Centaur (minor planet)
Centaurus (constellation)
Centaurus A (NGC 5128)
Centaurus Cluster
Centaurus X-3
Center for Astronomical Adaptive Optics (CAAO)
central meridian
Cepheid variable
Cepheus (constellation) ...
Separated by only about a degree and a half, the western of the two, the "leader" as the stars cross the celestial sphere on their daily paths, is Yed Prior (the one that precedes), the eastern Yed Posterior (the one in back).
ZODIAC, imaginary belt in the celestial sphere, extending about 8° on either side of the Eliptic, the apparent path of the Sun among the stars.
The other two systems, including the vernal equinox, are fixed on the celestial sphere, and so seem to us to perform a diurnal revolution from east towards west.
Heraclides of Pontus (4th century BC) explained the apparent daily motion of the celestial sphere through the rotation of the Earth. The first person to present an argument for a heliocentric system, however, was Aristarchus of Samos (c. 270 BC).
Analemma (pronounced anna-lemma) is a term in astronomy used to describe the plot of the positions of the Sun on the celestial sphere at the same time of day (at approximately 24 hour intervals) and from the same location on Earth on successive ...
This 360-degree panoramic image, covering the entire celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet.
Orbits and celestial spheres do not have a unique center.
The center of the Earth is not the center of the Universe, but only the center of the mass and of lunar orbit.
The total field of view covered 1/4 of the celestial sphere. During its 11 month lifetime, EURECA tracked the Sun and WATCH gradually scanned across the entire sky.
Declination: One of two coordinates for the celestial sphere, which are analogous to latitude and longitude for the Earth's surface. The declination of an object is how many degrees it is north or south of the celestial equator.
The planispheric ~ represents the celestial sphere by a two-dimensional stereographic projection, showing the position of the sun and major stars at different times and dates, as well as different latitudes.
When the ancient astronomers look into the sky, they saw themselves at the center of a celestial sphere, with all of the planets and the Sun orbiting Earth.
The armillary sphere, a three-dimensional representation of the movements in the celestial sphere, was invented in Han China by the 1st century BCE.
In the equatorial system, the Earth's equator and poles are projected outward into space to form a celestial sphere with the Earth at the center. The projection of the Earth's equator onto this sphere is called the celestial equator.
Between one noon and the next, the Sun too moves slightly in the sky, as part of its annual circuit around the celestial sphere, discussed in the next section, on the ecliptic.
The Sun on the celestial sphere. The top frame shows the daily motion of the Sun around the Earth. The bottom shows the seasonal motion of the Sun through the zodiac. Diagram from Biblical Archaeology Review, September/October 1994.
Proper motion is the apparent motion of a star across the celestial sphere at right angles to the observer's line of sight; any radial motion (toward or away from the Sun) is not included.
The North Star is a star located close to the North Pole of the celestial sphere, i.e., the projection of the North Pole onto the sky. The North Star is current Polaris (right ascension , declination ) since it is closest to the north celestial pole.
From the Earth, the constellations seem to be struck on the inside of a hollow sphere known as the celestial sphere. This sphere appears to rotate around the Earth in an east-west direction every 24 hours.
The transverse (or tangential) velocity of an object is its motion across our line of sight as it appears on the celestial sphere. A star's proper motion depends on its actual transverse velocity and inversely with its distance from us.
Altitude is a measurement in mapping astronomical objects on the celestial sphere (the sky as visible from Earth). Altitude is the angle of the object from the observer's horizon. If an object is on the horizon, its altitude is 0 degrees.
5 days to return to the same point on the celestial sphere as referenced to the Sun because of the motion of the Earth around the Sun; this is called a synodic month (lunar phases as observed from the Earth are correlated with the synodic month).
south celestial pole Point on the celestial sphere directly above the Earth's south pole.
spacetime A synthesis of the three dimensions of space and of a fourth dimension, time; a hallmark of relativity theory.
celestial equator - A great circle on the celestial sphere 90° from the celestial poles; the circle of intersection of the celestial sphere with the plane of the earth's equator.
hemisphere A half of the celestial sphere that is divided into two halves by either the horizon, the celestial equator, or the ecliptic.
 See also: Earth, Sun, Time, Planet, Astronomy
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