An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 14 Search : spherical
Five-hundred-meter Aperture Spherical radio Telescope (FAST)

Fr.: FAST   

The 500 m diameter → radio telescope which is the largest → single-dish antenna in the world. It is an Arecibo type telescope nestled within a natural basin in China's remote and mountainous Dawodang, Kedu Town, in southeastern China's Guizhou Province. The → reflector consists of 4,450 triangular panels, each with a side length of 11 m. More than 2,000 → actuators are used, according to the feedback from the measuring system, to deform the whole reflector surface and directly correct for → spherical aberration. Several detectors are used to cover a frequency range of 70 MHz to 3 GHz.

five; → hundred; → meter; → aperture; → spherical; → radio; → telescope.


Fr.: sphérique   

Having the form of a sphere; of or pertaining to a sphere or spheres.

From → sphere + → -ic + → -al.

spherical aberration
  بیراهش ِ کُره‌ای   
birâheš-e koreyi

Fr.: aberration sphérique, ~ de sphéricité   

An aberration of a spherical lens or mirror in which light rays converge not to a single point but to a series of points with different distances from the lens or mirror. Spherical aberration is corrected by using parabolic reflecting and refracting surface

spherical; → aberration.

spherical angle
  زاویه‌ی ِ کُره‌ای   
zâviye-ye koreyi

Fr.: angle sphérique   

An angle formed on the surface of a sphere by the intersection of two great circles of the sphere.

spherical; → angle.

spherical astrolabe
  اسطرلاب ِ سپهری، ~ کره‌ای   
ostorlâb-e sepehri, ~ kore-yi

Fr.: astrolabe sphérique   

A type of → astrolabe in which the observer's horizon is drawn on the surface of a globe, mounted with a freely rotating spherical lattice work or 'spider' representing the celestial sphere. The earliest description of the spherical astrolabe dates back to  the Iranian astronomer Nayrizi (865-922).

spherical; → astrolabe.

spherical astronomy
  اخترشناسی ِ کُره‌ای   
axtaršenâsi-ye kore-yi

Fr.: astronomie sphérique   

The branch of astronomy that is concerned with determining the apparent positions and motions of celestial bodies on the celestial sphere. Same as → positional astronomy.

spherical; → astronomy.

spherical coordinates
  هماراها‌ی ِ کره‌ای   
hamârâhâ-ye kore-yi

Fr.: coordonnées sphériques   

A coordinate system using an origin (O) and three perpendicular axes (Ox, Oy, Oz), in which the position of a point (P) is given by three numbers (r, θ, φ). The coordinate r is the distance from the origin, θ the angle between the z-axis and the r direction, and φ the angle between the projection of r on the xy-plane and the Ox-axis. The coordinate φ is also called the → azimuthal angle.

spherical; → coordinate.

spherical excess
  فزونی ِ سپهری، ~ کره‌ای   
fozuni-ye sepehri, ~ kore-yi

Fr.: excès sphérique   

The difference between the sum of the three angles of a → spherical triangle and 180° (π radians).

spherical; → excess.

spherical geometry
  هندسه‌ی ِ کُره‌ای   
hendese-ye kore-yi

Fr.: géométrie sphérique   

The branch of geometry that deals with figures on the surface of a sphere (such as the spherical triangle and spherical polygon). It is an example of a non-Euclidean geometry.

spherical; → geometry.

spherical harmonic
  هماهنگ ِ کره‌ای   
hamâhang-e kore-yi

Fr.: fonction harmonique sphérique   

A solution of some mathematical equations when → spherical polar coordinates are used in investigating physical problems in three dimensions. For example, solutions of → Laplace's equation treated in spherical polar coordinates. Spherical harmonics are ubiquitous in atomic and molecular physics and appear in quantum mechanics as → eigenfunctions of → orbital angular momentum. They are also important in the representation of the gravitational and magnetic fields of planetary bodies, the characterization of the → cosmic microwave background anisotropy, the description of electrical potentials due to charge distributions, and in certain types of fluid motion.

The term spherical harmonics was first used by William Thomson (Lord Kelvin) and Peter Guthrie Tait in their 1867 Treatise on Natural Philosophy; → spherical; → harmonic.

spherical latitude
  ورونای ِ کره‌ای، ~ سپهری   
varunâ-ye kore-yi, ~ sepehri

Fr.: latitude sphérique   

The angle between the → normal to a spherical reference surface and the → equatorial plane.

spherical; → latitude.

spherical polar coordinate
  هماراهای ِ کره‌ای ِ قطبی   
hamârâhâ-ye kore-yi-ye qotbi

Fr.: coordonnées sphériques polaires   

Same as → spherical coordinates.

spherical; → polar; → coordinate

spherical symmetry
  همامونی ِ کُره‌ای   
hamâmuni-ye kore-yi

Fr.: symétrie sphérique   

A configuration in which the constituting parts are arranged concentrically around the center of a sphere.

spherical; → symmetry.

spherical triangle
  سه‌بر ِ کُره‌ای   
sebar-e kore-yi

Fr.: triangle sphérique   

A triangle drawn on the → surface of a → sphere. A spherical triangle, like a plane triangle, may be right, obtuse, acute, equilateral, isosceles, or scalene. The sum of the angles of a spherical triangle is greater than 180° (π) and less than 540° (3π). See also → spherical excess.

spherical; → triangle.