An Etymological Dictionary of Astronomy and Astrophysics

To have, produce, or generate oscillations. → vibrate.

Etymology (EN): From L. oscillatus, p.p. of oscillare “to swing,” from oscill(um) “swing” + -ate a suffix forming verbs from L. words.

Etymology (PE): Navidan “to swing, oscillate,” from nâvidan, literally “to swing like a ship,” from nâv “ship;” O.Pers./Av. *nāv-, O.Pers. nāviyā- “fleet;” Skt. nau-, nava- “ship, boat;” Gk. naus “ship;”
PIE *nau- “boat.”

To have, produce, or generate oscillations. → vibrate.

Etymology (EN): From L. oscillatus, p.p. of oscillare “to swing,” from oscill(um) “swing” + -ate a suffix forming verbs from L. words.

Etymology (PE): Navidan “to swing, oscillate,” from nâvidan, literally “to swing like a ship,” from nâv “ship;” O.Pers./Av. *nāv-, O.Pers. nāviyā- “fleet;” Skt. nau-, nava- “ship, boat;” Gk. naus “ship;”
PIE *nau- “boat.”

A cosmological model in which the Universe is closed and undergoes a series of oscillations, each beginning with a big bang and ending with a big crunch.

See also: Oscillating, verbal adj. of → oscillate; → universe.

A cosmological model in which the Universe is closed and undergoes a series of oscillations, each beginning with a big bang and ending with a big crunch.

See also: Oscillating, verbal adj. of → oscillate; → universe.

The state of any quantity when the value of that quantity is continually changing so that it passes through maximum and minimum values.

See also: Verbal noun of → oscillate.

The state of any quantity when the value of that quantity is continually changing so that it passes through maximum and minimum values.

See also: Verbal noun of → oscillate.

Same as → pulsation mode.

See also: → oscillation; → mode.

Same as → pulsation mode.

See also: → oscillation; → mode.

A device for producing sonic or ultrasonic pressure waves in a medium. A device with no rotating parts for converting direct current into alternating current.

See also: Agent noun of → oscillate.

A device for producing sonic or ultrasonic pressure waves in a medium. A device with no rotating parts for converting direct current into alternating current.

See also: Agent noun of → oscillate.

A quantum-mechanical measure of the probability that a specific atomic transition
will occur. It is used in the equation for the absorption coefficient of a spectral line. Also known as f value.

See also: → oscillator; → strength.

A quantum-mechanical measure of the probability that a specific atomic transition
will occur. It is used in the equation for the absorption coefficient of a spectral line. Also known as f value.

See also: → oscillator; → strength.

Geometry: Of a curve, to touch another curve so as to have the same tangent and curvature at the point of contact.

Etymology (EN): From L. osculatum p.p. of osculari “to kiss,” from osculum “kiss,” literally “little mouth,” diminutive of os “mouth;” PIE *os-/*ous- “mouth;” cf. Av. āh- “mouth;” Skt. ās-, āsán- “mouth;” Hittite aiš- “mouth;” O.Ir. á “mouth;” O.N. oss “mouth.”

Etymology (PE): Âbusidan, from â- a nuance prefix + busidan “to kiss,” related to buyidan “to smell,” buy “smell, scent;” Mid.Pers. bôy, bôd “smell, scent; consciousness,” bôyidan “to smell,” Mod./Mid.Pers. bustân “garden,” Parthian (prefixed *pati-) pdbws- “to desire; to hope for;” Av. baod- “to perceive, notice, become aware of; to smell of,” baoδi- “smell, fragrance,” baozdri- “who gets to know sexually;”
cf. Skt. bodh- “to wake, awaken; to perceive, pay attention,” Buddha “awakened, enlightened;” Gk. peuthomai “to learn, hear;” Lith. budeti “to wake;” O.C.S. bljusti “to take care;” PIE base *bheudh- “to be aware, to make aware.”

Geometry: Of a curve, to touch another curve so as to have the same tangent and curvature at the point of contact.

Etymology (EN): From L. osculatum p.p. of osculari “to kiss,” from osculum “kiss,” literally “little mouth,” diminutive of os “mouth;” PIE *os-/*ous- “mouth;” cf. Av. āh- “mouth;” Skt. ās-, āsán- “mouth;” Hittite aiš- “mouth;” O.Ir. á “mouth;” O.N. oss “mouth.”

Etymology (PE): Âbusidan, from â- a nuance prefix + busidan “to kiss,” related to buyidan “to smell,” buy “smell, scent;” Mid.Pers. bôy, bôd “smell, scent; consciousness,” bôyidan “to smell,” Mod./Mid.Pers. bustân “garden,” Parthian (prefixed *pati-) pdbws- “to desire; to hope for;” Av. baod- “to perceive, notice, become aware of; to smell of,” baoδi- “smell, fragrance,” baozdri- “who gets to know sexually;”
cf. Skt. bodh- “to wake, awaken; to perceive, pay attention,” Buddha “awakened, enlightened;” Gk. peuthomai “to learn, hear;” Lith. budeti “to wake;” O.C.S. bljusti “to take care;” PIE base *bheudh- “to be aware, to make aware.”

Relating to → osculate.

See also: Participial adjective of → osculate.

Relating to → osculate.

See also: Participial adjective of → osculate.

The circle that touches a curve (on the concave side) and whose radius is the radius of curvature.

See also: → osculating; → circle.

The circle that touches a curve (on the concave side) and whose radius is the radius of curvature.

See also: → osculating; → circle.

The orbital elements of an osculating orbit.

See also: → osculating; → element.

The orbital elements of an osculating orbit.

See also: → osculating; → element.

The Keplerian orbit that a satellite would follow after a specific time t if all forces other than central inverse-square forces ceased to act from time t on.
An osculating orbit is tangent to the real, perturbed, orbit and has the same velocity at the point of tangency.

See also: → osculating; → orbit.

The Keplerian orbit that a satellite would follow after a specific time t if all forces other than central inverse-square forces ceased to act from time t on.
An osculating orbit is tangent to the real, perturbed, orbit and has the same velocity at the point of tangency.

See also: → osculating; → orbit.

For a curve C at a point p, the limiting plane obtained from taking planes through the tangent to C at p and containing some variable point p’ and then letting p’ approach p along C.

See also: → osculating; → plane.

For a curve C at a point p, the limiting plane obtained from taking planes through the tangent to C at p and containing some variable point p’ and then letting p’ approach p along C.

See also: → osculating; → plane.

For a curve C at a point p, the limiting sphere obtained by taking the sphere that passes through p and three other points on C and then letting these three points approach p independently along C.

See also: → osculating; → sphere.

For a curve C at a point p, the limiting sphere obtained by taking the sphere that passes through p and three other points on C and then letting these three points approach p independently along C.

See also: → osculating; → sphere.

The contact between two osculating curves or the like.

See also: Verbal noun of → osculate

The contact between two osculating curves or the like.

See also: Verbal noun of → osculate

A → spacecraft whose goal is to collect a sample from the asteroid → 101955 Bennu and bring it back to Earth. It was launched by → NASA on September 8, 2016. OSIRIS-REx will spend two years chasing Bennu down, finally rendezvousing with the → near-Earth asteroid in August 2018. The spacecraft will then study the → asteroid Bennu from orbit for another two years before grabbing at least 60 grams of surface material in July 2020. The sample should reach Earth in 2023. The analysis of the sample would allow to study the role that → B-type asteroids like Bennu, which are primitive and apparently carbon-rich, may have played in helping life appear on Earth.

See also: The name is short for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer .

A → spacecraft whose goal is to collect a sample from the asteroid → 101955 Bennu and bring it back to Earth. It was launched by → NASA on September 8, 2016. OSIRIS-REx will spend two years chasing Bennu down, finally rendezvousing with the → near-Earth asteroid in August 2018. The spacecraft will then study the → asteroid Bennu from orbit for another two years before grabbing at least 60 grams of surface material in July 2020. The sample should reach Earth in 2023. The analysis of the sample would allow to study the role that → B-type asteroids like Bennu, which are primitive and apparently carbon-rich, may have played in helping life appear on Earth.

See also: The name is short for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer .

A very hard, brittle metal belonging to the → platinum group elements; symbol Os. → Atomic number 76, → atomic weight 190.2, → melting point 3,045 °C, → boiling point 5,027 °C, → specific gravity 22.57 at 20°C. It was discovered in 1803 simultaneously with → iridium in a crude → platinum ore by the English chemist Smithson Tennant.

See also: From Gk. osme “smell” because of the sharp odor of the volatile oxide.

A very hard, brittle metal belonging to the → platinum group elements; symbol Os. → Atomic number 76, → atomic weight 190.2, → melting point 3,045 °C, → boiling point 5,027 °C, → specific gravity 22.57 at 20°C. It was discovered in 1803 simultaneously with → iridium in a crude → platinum ore by the English chemist Smithson Tennant.

See also: From Gk. osme “smell” because of the sharp odor of the volatile oxide.

The process by which solvent molecules pass through a partially permeable
membrane from a dilute solution into a more concentrated solution, thus equalizing the concentrations of materials on either side of the membrane. → permeability.

Etymology (EN): Extracted from Fr. endosmose “endosmosis” and exosmose “exosmosis,” from Gk. prefixed osmos “a thrusting, a pushing,” from othein “to push, to thrust;” cf. Av. vādāiiôit “breaks through, hunts,” vadah- “wedge;” Mod.Pers. guvah, gavah “wedge;” Skt. vadh- “to slay, kill,” vadha- “killer.”

Etymology (PE): Tarârân, literally “pushing across,” from tarâ-, → trans-, + rân present stem of rândan “to push, drive, cause to go,”
causative of raftan “to go, walk, proceed” (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- “to go; to attack”).

The process by which solvent molecules pass through a partially permeable
membrane from a dilute solution into a more concentrated solution, thus equalizing the concentrations of materials on either side of the membrane. → permeability.

Etymology (EN): Extracted from Fr. endosmose “endosmosis” and exosmose “exosmosis,” from Gk. prefixed osmos “a thrusting, a pushing,” from othein “to push, to thrust;” cf. Av. vādāiiôit “breaks through, hunts,” vadah- “wedge;” Mod.Pers. guvah, gavah “wedge;” Skt. vadh- “to slay, kill,” vadha- “killer.”

Etymology (PE): Tarârân, literally “pushing across,” from tarâ-, → trans-, + rân present stem of rândan “to push, drive, cause to go,”
causative of raftan “to go, walk, proceed” (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- “to go; to attack”).

The hydrostatic pressure produced on the surface of a partially permeable membrane by osmosis.

See also: → osmotic; → pressure.

The hydrostatic pressure produced on the surface of a partially permeable membrane by osmosis.

See also: → osmotic; → pressure.

An approximate empirical criterion for the stability of a → galactic disk against its collapse to form a bar. The disk is stable if the following relation holds: T/|W| < 0.14, where T is the rotational → kinetic energy and |W| is the absolute value of the gravitational → potential energy. While the → Toomre criterion applies only to small linear perturbations, the Ostriker-Peebles criterion describes global modes.

See also: Ostriker & Peebles, 1973, ApJ 186, 467; → criterion.

An approximate empirical criterion for the stability of a → galactic disk against its collapse to form a bar. The disk is stable if the following relation holds: T/|W| < 0.14, where T is the rotational → kinetic energy and |W| is the absolute value of the gravitational → potential energy. While the → Toomre criterion applies only to small linear perturbations, the Ostriker-Peebles criterion describes global modes.

See also: Ostriker & Peebles, 1973, ApJ 186, 467; → criterion.