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

A satellite orbit in the plane of the Earth's equator and 35,880 km above it, at which distance the satellite's period of rotation matches the Earth's and the satellite always remains fixed in the same spot over the Earth.

Geostationary, from → geo- + → stationary; → orbit.

Having a fixed, unchanging position; motionless. geostationary orbit

M.E. from L. stationarius, in classical L., "of a military station," from statio, → station.

Isatvar, from ist present stem of istâdan "to stand" (Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand") + -var suffix of possession, variant -ur (Mid.Pers. -uwar, -war; from O.Pers. -bara, from bar- "to bear, carry").

A → black hole with zero → angular momentum, that does not rotate.

→ stationary; → black hole.

A property of → space-time outside a → rotating black hole, which consists of a surface which geometrically bounds the → ergosphere outward. At the stationary limit a particle would have to move with the local light velocity in order to appear stationary to a distant observer. This is because the space here is being dragged at exactly the speed of light relative to the rest of space. Outside this limit space is still dragged, but at a rate less than the speed of light. Also known as → static limit.

→ stationary; → limit; → surface.

Electronics: A random noise whose intensity remains constant with time.

→ stationary; → noise.

An orbit in which the satellite revolves about the primary at the angular rate at which the primary rotates on its axis. From the primary, the satellite thus appears to be stationary over a point on the primary.

→ stationary; → orbit.

Mechanics: The condition of a body or system at rest.

→ stationary; → phase.

1) Math.: For a → function y = f(x), a point at which the → tangent to the graph is horizontal. In other words, a point where the → slope is zero: dy/dx = 0.
2) Of a planet, the position at which the rate of change of its apparent → right ascension is momentarily zero.

→ stationary; → point.

An artificial satellite in a synchronous orbit. → geostationary orbit

→ stationary; → satellite.

A → time series if it obeys the following criteria: 1) Constant → mean over time (t). 2) Constant → variance for all t, and 3) The → autocovariance function between X_t1 and X_t2 only depends on the interval t₁ and t₂.

→ stationary; → time; → series.

Same as → standing wave.

→ stationary; → wave.