An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The angle between the → incident radiation on a → particle (such as a water droplet in a rainbow) and the scattered radiation (such as the light ray leaving the droplet). Scattering angle is a function of → impact parameter. In other words, The angle along which the change of direction has taken place, irrespective whether radiation is scattered by particles or reflected (refracted) by a surface.

→ scattering; → angle.

Low angle, → grazing incidence.

→ shallow; → angle.

The angle on the celestial sphere measured westward from the hour circle of the vernal equinox to that of the celestial body.

→ sidereal; → hour angle.

The figure formed by three or more planes meeting at a common point or formed at the vertex of a cone. The solid angle completely surrounding a point is 4π steradian. → steradian.

→ solid; → angle.

Zâviyé, → angle; fazâyi "of or relating to space," → space; jâmed, → solid.

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

→ spherical; → angle.

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.

An angle whose two sides pass through the endpoints of an arc.

Subtended p.p. of → subtend; → angle.

The triangular shape formed by the three bright stars → Altair, → Deneb, and → Vega on the northern hemisphere's → celestial sphere, particularly visible during the summer months.

→ summer; → triangle.

The angle that when added to a given angle makes 180°. → complementary angle.

→ supplementary; → angle.

The angle a rocket makes with the vertical as it curves along its trajectory.

→ tilt; → angle.

The plane figure formed by three lines intersecting in pairs at three points; a three-sided → polygon. → equilateral triangle, → isosceles triangle, → scalene triangle.

M.E., from O.Fr. triangle, from L. triangulum "triangle," from neuter of adj. triangulus "three-cornered," from tri-, → three, + angulus "corner," → angle.

Seguš "three-cornered," from sé, → three, + guš "corner, → angle."
Sebar "three-sided," from sé, → three, + bar "→ side; breadth; breast."

1) A theorem according to which any side of a triangle is always shorter than the sum of the other two sides.
2) The third requirement for a → distance function describing a → metric space.

→ triangle; → inequality.

The maximum angle at which a display, such as a TV screen, can be viewed with acceptable visual performance.

Viewing, from view, M.E. v(i)ewe (n.); M.Fr. veue "sight," feminine p.p. of veoir "to see," from L. videre "to see," → vision; → angle.

Zâviyé, → angle; did→ vision.

An international collaboration, more accurately named SuperWASP, led by the United Kingdom, that aims at detecting → extrasolar planets by means of the → transit method. SuperWASP consists of two robotic observatories that operate continuously all year around, providing coverage of the sky in both hemispheres. The first, SuperWASP-North, is located on the island of La Palma. The second, SuperWASP-South, is located at the site of the South African Astronomical Observatory (SAAO). The observatories each consist of eight wide-angle cameras that simultaneously monitor the sky for → planetary transit events. Using the array of cameras makes it possible to monitor millions of stars simultaneously at an → apparent visual magnitude from about 7 to 13.

→ wide; → angle; → search; → planet.