An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 39 Search : real
real number
  عدد ِ هسیا   
adad-e hasyâ

Fr.: nombre réel   

A number that can be represented by a point on a line. The set of real numbers includes all rational and irrational numbers, but not the imaginary numbers.

real; → number.

real object
  بر‌آخت ِ هسیا   
baâxt-e hasyâ

Fr.: objet réel   

In an optical system, a collection of points which actually serves as a source of light rays.

real; → object.

real-time operation
  آپارش در زمان ِ هسیا   
âpâreš dar zamân-e hasyâ

Fr.: opération en temps réel   

The operation of a computer during the actual time that the related physical processes take place so that the results can be used to guide the physical processes.

real; → time; → operation.

real-time processing
  آمایش در زمان ِ هسیا   
âmâyeš dar zamân-e hasyâ

Fr.: traitement en temps réel   

Data processing that takes place instantaneously upon data entry or receipt of a command.

real; → time; → processing.

realism
  هسیاگرایی؛ هسیاباوری   
hasyâgerâyi; hasyâbâvari

Fr.: réalisme   

1) An inclination or concern for the actual or real, as distinguished from the abstract or speculative.
2) Philo.: The doctrine that material objects exist independently of our perception of them.
3) Art, literature: The attempt to describe the objects or social conditions as they actually are, without idealization or presentation in abstract form.

real; → -ism.

realist
  ۱) هسیاگرا، هسیاباور؛ ۲) هسیامند   
1) hasyâgerâ, hasyâbâvar; 2) hasyâmand

Fr.: réaliste   

1) A person who tends to view or represent things as they really are; an adherent of → realism.
2) Of or pertaining to realism or to a person who embodies its principles or practices.

real; → -ist.

realistic
  هسیامند   
hasyâmand

Fr.: réaliste   

1) Interested in, concerned with, or based on what is real or practical.
2) Philo.: Of or pertaining to realists or → realism.

From → real + -istic, from L. -isticus, Gk. -istikos, from -ikos, → -ic.

reality
  هسیایی   
hasyâi

Fr.: réalité   

1) The state or quality of being real. A real thing or fact.
2) Philo.: The totality of what is, as opposed to what merely seems to be.

real + → -ity.

really
  هسیانه   
hasyâné

Fr.: vraiment   

In reality; actually; indeed.

real; → -ly.

sidereal
  اختری   
axtari (#)

Fr.: sidéral   

Of, relating to, or determined by or from stars.

From M.Fr. sidereal, from L. sidereus "starry, astral," from sidus (genitive sideris) "star, constellation."

Axtari, pertaining to axtar "star," probably a variant of setâréstar.

sidereal day
  روز ِ اختری   
ruz-e axtari (#)

Fr.: jour sidéral   

The period of → Earth's rotation around its axis, the mean value of which is about 23h 56m 04.092s (23.934 470 hours). In other words, the interval between two successive passages of a star across a given → meridian. The sidereal day is 3 minutes 56 seconds shorter than the → mean solar day. The reason is that Earth moves a little less than a degree around the Sun during the time it takes for one full axial rotation. So, for the Sun to appear on the same meridian in the sky again after one full axial rotation, the Earth has to rotate one extra degree to bring the Sun into the same apparent meridian in the sky. This is also why the stars rise and set about 4 min earlier each day.

sidereal; → day.

sidereal hour angle
  زاویه‌ی ِ ساعتی ِ اختری   
zâviye-ye sâ'ati-ye axtari (#)

Fr.: angle horaire   

The angle on the celestial sphere measured westward from the hour circle of the vernal equinox to that of the celestial body.

sidereal; → hour angle.

sidereal month
  ماه ِ اختری   
mâh-e axtari (#)

Fr.: mois sidéral   

The time taken by the Moon to complete one → revolution around the Earth with respect to a background, → fixed star. The average time is 27.321 661 days (27d 7h 43m 11.5s). Same as → lunar sidereal orbital period.

sidereal; → month.

sidereal period
  دوره‌ی ِ اختری   
dowre-ye axtari (#)

Fr.: période sidérale   

sidereal revolution period; → sidereal rotation period.

sidereal; → period.

sidereal revolution period
  دوره‌ی ِ گردش ِ اختری   
dowre-ye gardeš-e axtari (#)

Fr.: période de révolution sidérale   

The time taken by a planet or satellite to complete one revolution about its primary with respect to stars. For Earth, same as → sidereal year.

sidereal; → revolution; → period.

sidereal rotation period
  دوره‌ی ِ چرخش ِ اختری   
dowre-ye carxeš-e axtari

Fr.: période de rotation sidérale   

The rotation period of a celestial body with respect to fixed stars. For Earth, same as → sidereal day.

sidereal; → rotation; → period.

sidereal time
  زمان ِ اختری   
zamân-e axtari (#)

Fr.: temps sidéral   

The time based upon → Earth's rotation with respect to the stars, with the → sidereal day as the unit of measurement. At the moment when the → vernal equinox crosses the → meridian in → upper culmination, sidereal time is equal to zero hours for that observing position. The → hour angle of the vernal equinox is equal to sidereal time.

sidereal; → time.

sidereal year
  سال ِ اختری   
sâl-e axtari (#)

Fr.: année sidérale   

The interval between two successive passages of the Sun, in its apparent → annual motion around the → celestial sphere, through a particular point relative to stars. It is equal to 365.256356 days for the J2000.0 epoch and is 20m 24.5s longer than the → tropical year.

sidereal; → year.

true sidereal time
  زمان ِ اختری ِ راستین   
zamân-e axtari-ye râstin

Fr.: temps sidéral vrai   

The → sidereal time with respect to the → true equinox.

true; → sidereal; → time.

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