# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 10 Search : geometric
 geometric   هندسی   hendesi (#)Fr.: géométrique   Of or pertaining to geometry or to the principles of geometry.Adj. of → geometry geometric albedo   سپیدای ِ هندسی   sepidâ-ye hendesiFr.: albedo géométrique   A measure of the → reflectivity of a surface, especially of the solar system bodies (planets, satellites or asteroids). It is the ratio of a body's brightness at zero → phase angle to the brightness of a perfectly diffusing disk with the same position and apparent size as the body. Geometric albedo depends on the radiation wavelength. The bolometric geometric albedo refers to reflectivity in all wavelengths. Compare with the → Bond albedo.→ geometric; → albedo. geometric delay   درنگ ِ هندسی   derang-e hendesiFr.: retard géométrique   One of the two factors contributing to → gravitational lensing time delay that arises from the fact that the bent trajectory is longer than the straight one. The other factor is due to the → Shapiro time delay.→ geometric; → delay. geometric horizon   افق ِ هندسی   ofoq-e hendesiFr.: horizon géométrique   Where the apparent → sea horizon would be if there were no → atmospheric refraction.→ geometric; → horizon. geometric mean   میانگین ِ هندسی   miyângin-e hendesi (#)Fr.: moyenne géométrique   The middle term in a → geometric progression. Of two terms, the geometric mean is the square root of their product. For example, the geometric mean of 4 and 9 is ± 6. For a series of n terms, it is expressed as: (a1.a2. ... .an)1/n.→ geometric; → mean. geometric optics   نوریک ِ هندسی   nurik-e hendesiFr.: optique géométrique   A branch of physics that deals with reflection and refraction of rays of light without reference to the wave or physical nature of light.→ geometric; → optics. geometric progression   فرایازی ِ هندسی   farâyâsi-e hendesi (#)Fr.: progression géométrique   A → sequence in which the ratio of a term to its predecessor is the same for all terms. In general, the nth term has the form ar(n-1), where n is a positive integer, and a and r are nonzero constants; r is called the ratio or common ratio. The sum of the first n terms is given by: Sn = a(1 - rn)/(1 - r). Also called → geometric sequence.→ geometric; → progression. geometric scattering   پراکنش ِ هندسی   parâkaneš-e hendesiFr.: diffusion géométrique   A type of scattering in which the wavelength (of the light or the sound) is much smaller than the size of object causing the scattering.→ geometric; → scattering. geometric sequence   پی‌آیه‌ی ِ هندسی   peyâye-ye hendesiFr.: suite géométrique   → geometric; → sequence. geometrical libration   رخگرد ِ هندسی   roxgard-e hendesi (#)Fr.: libration géométrique   Libration resulting from changes in the location of the observer with respect to body. More specifically, a lunar libration motion that results from the Earth based observer seeing the Moon from different directions at different times. There are three types of geometrical libration: → libration in longitude, → libration in latitude, and → diurnal libration. See also → physical libration.→ geometric; → libration.