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

1) An → imaginary point in the → southern hemisphere representing the intersection of the → Earth's → rotation axis with the → globe with the → celestial sphere.
2) For a → magnet, the pole which points toward the geographic south.
3) In a → magnetic field, the point which receives a → line of force coming from the → north pole.

→ south; → pole.

A star that would mark the south → celestial pole. Presently no bright visible star is situated along the → rotation axis of the Earth in the southern hemisphere. But, because of the Earth's → axial precession, about 7,000 years from now the star → Delta Velorum in the constellation → Vela, the Sail, will come to within 0.2 degrees of the South Celestial Pole (around the year 9250 B.C.). That is closer to marking the celestial pole than → Polaris or → Sirius ever do during their reigns as pole stars! Sirius will become the South Pole Star some 60 thousand years from now (around the year 66270 B.C.). In that time, Sirius will come to within 1.6 degrees of the South Celestial Pole.

→ south; → celestial; → pole.

Of or pertaining to the south.

M.E., O.E. suðerne, from suð, → south, + -erne, suffix denoting direction.

Daštari, relating to daštar, → south.

Popular name for the constellation → Crux. Its four brightest stars form a distinctive cross shape.

→ southern; → Crux.

The half of the → Earth or another → north pole between the → south pole and the → equator.

→ southern; → hemisphere.

The transit of a celestial object, especially the Sun, across the meridian due south of the observer.

Verbal noun from → south (v.).

Gozar-e daštar-su, literally "passage southward," from gozar, → passage; daštar→ south; su, → direction.

The ratio of the → molar heat of vaporization of any liquid to its → boiling point is a constant, about 88 joules per mole per Kelvin. The rule is equivalent to the statement that the → entropy of vaporization is constant. It is not always followed, especially by liquids such as water in which hydrogen bonding occurs between the molecules.

Named after Frederick Thomas Trouton (1863-1922), an Irish physicist; → rule.

An experiment first carried out in 1903 to reveal the absolute motion of the Earth with respect to the → ether. The experiment consists of detecting a torque on a charged parallel-plate → capacitor that was suspended so that its plates were vertical. Since the Earth moves around the Sun, the moving charges were expected to produce magnetic fields, and the resulting torque should tend to turn the capacitor bringing its plates parallel to its velocity. No such effect was observed, and the absence of the torque supports the theory of → special relativity.

Named after Frederick T. Trouton (1863-1922) and Henry R. Noble; → experiment.

A spinning column of rising humid air that occurs over a body of warm water. Waterspouts fall within the class of atmospheric phenomena known as convective vortices that includes → tornadoes, → dust devils, and → hurricanes. They can feature wind speeds over 200 kilometers per hour.

→ water + spout, from M.E. spouten akin to M.Du. spiten "to spout;" O.E. spiwan "to spew."

Tanure-ye daryâyi, from tanuré (kešidan) "turning and raising in the air," probably from tanidan "to turn, spin," → tension; daryâyi, → marine.

Same as → paradox of youth.