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

An set of points such that the distance between every pair of points is defined by a → distance function with the following properties: 1) the distance from the first point to the second equals zero if and only if the points are the same, 2) the distance from the first point to the second equals the distance from the second to the first, and 3) the sum of the distance from the first point to the second and the distance from the second point to a third exceeds or equals the distance from the first to the third.
In mathematical language, the properties, for a nonempty set X, can be expressed as:
1) d(x,y)≥ 0 and d(x,y) = 0 if and only if x = y.
2) d(x, y) = d(y,x) for all x, y ∈ X.
3) d(x,z)≤ d(x,y) + d(y,z) for all x, y, and z ∈ X. Also called → triangle inequality.

→ metric; → space.

A → NASA funded project to support and provide to the astronomical community a variety of astronomical data archives, with the primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum. MAST is a huge database that contains astronomical observations of stars, planets and galaxies from 16 separate NASA space science missions, including the Hubble Space Telescope. It is located at the Space Telescope Science Institute (STScI).

In honor of senator Barbara A. Mikulski for her active support for science, NASA, and the astrophysics community; → archive; → space; → telescope.

A completely flat four-dimensional space, which contains no gravitating matter, used in the theory of special relativity.

→ Minkowski metric; → space-time.

A small telescope dedicated entirely to → asterolseismology. MOST is the first space telescope entirely designed and constructed by Canada. It was launched into space in 2003. The satellite weighs only 54 kg and is equipped with an ultra high precision telescope that measures only 15 centimetres in diameter. Despite its tiny size, it is ten times more sensitive than the → Hubble Space Telescope in detecting the minuscule variations in a star's luminosity caused by vibrations that shake its surface. MOST completes one orbit around the Earth every 101 minutes by passing over each of Earth's poles.

MOST, short for Microvariability and Oscillations of STars telescope.

A federal agency of the United States government founded in 1958 for civil aeronautical research and space exploration, superseding the National Advisory Committee for Aeronautics (NACA). Its goals include improving human understanding of the universe, the solar system, and Earth and establishing a permanent human presence in space. NASA is headquarted at Washington, D.C., and operates several research, development, and test facilities, as follows alphabetically: 1) Ames Research Center; 2) Dryden Flight Research Facility at Edwards, California, used for flight testing and as a landing site for the Space Shuttle; 3) Glenn Research Center at Cleveland, Ohio, concerned with aircraft and rocket propulsion; 4) Goddard Space Flight Center; 5) Jet Propulsion Laboratory; 6) Johnson Space center; 7) Kennedy Space Center; 8) Langley Research Center at Hampton, Virginia, which carries out research in aeronautics and space technology; 9) Marshall Space Flight Center; 10) the Space Telescope Science Institute; 11) Stennis Space Center, near Bay St Louis, Mississippi, for testing rocket engines; and 12) Wallops Flight Facility on Wallops Island, Virginia, which manages NASA's sounding rocket and scientific balloon programs.

→ national; → aeronautics; → space; administration, verbal noun of administer, from M.E. amynistre, from O.Fr. aministrer, from L. administrare "to serve, carry out, manage," from → ad- "to" + ministrare "to serve," from minister "servant, priest's assistant," from minus, minor "less," hence "subordinate," + comparative suffix *-teros.

Sâzmân, → organization; fazâyi pertaining to fazâ, → space; Âmrikâ "United State of America."

In an → optical system, the space between the object being viewed and the → entrance pupil. See also → image space.

→ object; → space.

A space of infinite volume without any boundary. Triangles which lie on the surface of an open space will have a sum of angles which is less than 180°. An open space has a negative → curvature. See also → open Universe, → closed space.

→ open; → space.

The space beyond the Earth's atmosphere.

→ outer; → space.

Of a dynamical system, a six-dimensional space consisting of the set of values that the position and velocity can take together (x, y, z, v_x, v_y, v_z). → velocity space.

→ phase; → space.

A real vector space of dimension n having a symmetric bilinear form (x, y) such that in some basis e₁, ..., e_n, the quadratic form (x²) takes the form x₁² + ... + x_{n - 1}² - x_n². Such bases are called orthonormal.

→ pseudo-; → Euclidean; → space.

A space with an affine connection (without torsion), at each point of which the tangent space is a → pseudo-Euclidean space (Encyclopedia of Mathematics, Kluwer Academic Publications, Editor in chief I. M. Vinogradov, 1991).

→ pseudo-; → Riemannian; → space.

The space corresponding to → redshift measurements, as contrasted with real space. See also → redshift space distortion

→ redshift; → space.

The distortion observed in → redshift space of → galaxy clusters caused by peculiar velocities of the members (→ peculiar velocity). In a perfectly homogeneous → Friedmann-Lemaitre Universe the redshifts would accurately measure radial distances from the observer, and the mapping from real space to redshift space would simply be an identity. In an inhomogeneous Universe the peculiar velocities associated with any inhomogeneous structure will introduce a distortion in this mapping (N. Kaiser, 1987, MNRAS 227, 1). See also: → fingers of God, → Kaiser effect.

→ redshift; → space; → distortion;.

Statistics: A set which consists of all possible outcomes of a random experiment.

→ sample; → space.

1) Physics: That part of the boundless four dimensional continuum in which matter can be physically extended.
2) Astro.: That part of the Universe which lies beyond the Earth's atmosphere and in which the density of matter is low. Also known as outer space.

M.E., from O.Fr. espace, from L. spatium "room, area, distance, stretch of time," of unknown origin.

Fazâ, loan from Ar.

Electricity: An electric charge belonging to a cloud of electrons lying between a cathode and plate within an electric tube.
Geophysics: An excess of either negatively or positively charged ions in a layer of the atmosphere, giving that layer either a negative or positive charge.

→ space; → charge.

Man-made objects in orbit around the Earth that no longer serve any useful purpose. The estimated number of debris include about 22,000 tractable objects larger than 10 cm in all orbits, of which 2,200 are dead satellites and last stages of the rocket that put them in orbit. There are also left-overs from spacecraft and mission operations, such as bolts, lens caps, clamp bands, auxiliary motors, etc. The debris presents a threat because of their high speeds, which ranges between 15 and 20 km/sec. Also called space junk, space waste, orbital debris.

→ space; → debris.

A travel outside the Earth by manned or unmanned vehicle requiring space technology.

→ space; → flight.

Set of operations (rotation about an axis, reflection across a plane, translation, or combination of these) which when carried out on a periodic arrangement of points in space brings the system of points to self-coincidence.

The word group comes from the mathematical notion of a group.

A manned or unmanned space flight outside the Earth's atmosphere.

→ space; mission, from L. missionem (nominative missio) "act of sending," from mittere "to send," of unknown origin.

Gosilân, from gosil, variant gosi "sending away, dismission;" Mid.Pers. wisé "to despatch" (Parthian Mid.Pers. wsys- "to despatch;" Buddhist Mid.Pers. wsydy "to despatch;" Sogdian 'ns'yd- "to exhort"), from Proto-Iranian *vi-sid- "to despatch, send off," from prefix vi- "apart, away, out," + *sid- "to call" + -ân nuance suffix; fazâyi adj. of fazâ, → space.