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

In the → phase diagram of a → mixture at constant pressure, (such as an → alloy), the → curve that separates the → liquid+solid → phase from the all solid phase. Above the solidus some or all of the mixture will be in a liquid state. See also → liquidus.

From L. solidus, → solid.

Math., Physics: A solution of a certain type of partial differential equation that represents a solitary wave. A soliton is a self-reinforcing wave that maintains its shape while it travels at constant speed. Solitons are caused by a cancellation of nonlinear and dispersive effects in the medium.

From solit(ary) + → -on.

Either of the two points on the → ecliptic at which the apparent → longitude of the → Sun is 90° or 270°. Also the time at which the Sun is at either point. Solstices occur when the Earth's axis is oriented directly toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes. → summer solstice, → winter solstice.

M.E., from O.Fr. solstice, from L. solstitium "point at which the sun seems to stand still," from sol, → sun, cognate with Pers. xor, xoršid, hur, as below, + p.p. stem of sistere "to come to a stop, make stand still," akin to Pers. istâdan "to stand," as below.

Xoristân, is composed of two components. The first one xor "sun," variant hur; Mid.Pers. xwar "sun;" Av. hū-, hvar- "sun;" cf. Skt. surya-, Gk. helios, L. sol, cognate with E. sun, as above; PIE base *sawel- "sun." The second component istân "standing," from istâdan "to stand;" Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthā- "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."

The great circle of the celestial sphere which passes through the poles of the celestial equator and the solstice points. → equinoctial colure.

Solsticial, adj. of → solstice; → colure.

The two points of the ecliptic the most distant from the equator.

Solsticial, adj. of → solstice; → point.

Chem.: Capable of being dissolved .

M.E., from M.Fr. soluble, from L.L. solubilis "that may be loosened or dissolved," from stem of L. solvere "loosen, dissolve," → solve.

Luyidani, from luyidan, → solve + -i, → -able.

Chem.: A substance which is dissolved in a solvent to form a solution.

From L. solutus, p.p. of solvere "to loosen, dissolve," → solve.

Luyešt, from luyešte, p.p. of luyeštan, variant of luyidan, → solve.

1) The act of solving a problem, question. The state of being solved.
2a) Math.: The process of determining the answer to a problem. The answer itself.
2b) Math.: Of a differential equation, any function which, when put into the equation, converts it into an identity.
3) Chem.: The process by which a gas, liquid, or solid is dispersed homogeneously in a gas, liquid, or solid without chemical change. a homogeneous, molecular mixture of two or more substances.

Verbal noun of → solve.

Any of a class of chemical reactions in which solute and solvent molecules combine.

From solv(ent), → solvent + -ation.

Luyé, from luy- the stem of luyidé→ solute and luyandé→ solvent + -é nuance suffix.

1) To find an answer or solution to; clear up; explain. related concept: → dissolve.
2) To make a solution of, as by mixing with liquid.

M.E. solven, from L. solvere "to loosen, dissolve, untie," from PIE *se-lu-, from reflexive pronoun *swe- + base *leu- "to loosen, divide, cut apart;" cf. Gk. lyein "to loosen, release, untie," O.E. -leosan "to lose," leas "loose;" E. lose, loose and Ger. los derive from this root.

Luyidan, infinitive from stem lu(y)-, from lu, variant of Mod.Pers. las "loose," lâ "slit, cut," luš "torn," lok "torn, piece," lâc "open, wide open;" lu, lunoti "to cut, sever, mow, pluck, tear asunder, destroy," lava "cutting, plucking; what is cut; fragment, piece;" Gk. lyein "to loosen, release, untie," as above. PIE *leu- "to loosen, divide, cut apart".

Substance having the power of dissolving other substances in it.

Agent noun of → solve.

The smallest detail that can be seen in an image. Same as → angular resolution.

→ spatial; → resolution.

The capacity of a spectrograph to separate two adjacent spectral lines. The theoretical spectral resolution depends on the grating dispersion, grating position, pixel size, collimator and camera focal length, and the entrance slit-width.

→ spectral; → resolution.

The point of the surface of a celestial body (including the Earth) at which the Sun is directly overhead at a particular time.

→ sub-; → solar; → point.

The moment in the northern hemisphere when the → Sun attains its highest → declination of 23°26' (or 23°.44) with respect the → equator plane. It happens when the Earth's axis is orientated directly toward the Sun, on 21 or 22 June. During the northern solstice the Sun appears to be directly overhead at noon for places situated at → latitude 23.44 degrees north, known as the → tropic of Cancer. The summer solstice can occur at any moment during the day. Two successive summer solstices are shifted in time by about 6 h. The summer solstice in the northern hemisphere is the → winter solstice in the southern hemisphere.

→ summer; → solstice.

The measure of the ability of an observing system to clearly separate events in time. In other words, the shortest time interval that can be determined between two different events.

→ temporal hour; → resolution.

Same → temporal resolution.

→ time; → resolution.

Describing an image whose constituent or elementary parts are not resolved. → unresolved source.

→ un- + → resolved.

A source of radiation whose angular size is too small for details of its structure to be revealed.

→ unresolved; → source.

The moment in the northern hemisphere when the → Sun attains its lowest → declination of -23°26' (or -23°.44) with respect the → equator plane. It happens when the Earth's axis is orientated directly away from the Sun, on 21 or 22 December. During the northern winter solstice the Sun appears to be directly overhead at noon for places situated at → latitude 23.44 degrees south, known as the → tropic of Capricorn. The winter solstice can occur at any moment during the day. Two successive winter solstices are shifted in time by about 6 h. The winter solstice in the northern hemisphere is the → summer solstice in the southern hemisphere.

→ winter; → solstice..