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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 7 Search : zenith
circumzenithal arc
  کمان ِ پیراسرسویی   
kamân-e pirâsarsui

Fr.: arc circumzénithal   

A colorful halo centered on the zenith, appearing when the solar elevation above the horizon is not too high (< 32°).

circum-; → zenithal; → arc.

geodetic zenith
  سرسوی ِ زمین‌سنجیک   
sarsu-ye zamin-sanjik

Fr.: zénith géodésique   

The intersection of the prolongation of the outward → normal to the → reference ellipsoid at the point in question with the → celestial sphere.

geodetic; → zenith.

zenith
  سرسو   
sarsu (#)

Fr.: zénith   

The point on the celestial sphere directly above the observer's head, opposite to the direction in which gravity acts. Opposite of → nadir.

M.E. cenith, from O.Fr. cenith, from M.L. cenit, senit, incorrect transliteration of Ar. samt (سمت) "path, direction," abbreviation of samt ar-ras (سمت‌الرأس), literally "road above one's head."

Sarsu, literally "the way over the head," from sarhead + su, → direction.

zenith distance
  دورای ِ سرسو، دوری ِ ~   
durâ-ye sarsu, duri-ye ~

Fr.: distance zénithale   

The angular distance of a celestial body from the zenith. The zenith distance is 90° minus the body's altitude above the horizon (i.e. the complement of the altitude) and hence is also known as coaltitude.

zenith; → distance

zenith telescope
  تلسکوپ ِ سرسو، دوربین ِ ~   
teleskop-e sarsu, dvrbin-e ~

Fr.: télescope zénithal   

A → telescope that is mounted on a → vertical axis or moves only a small amount from the vertical. It is primarily used to determine positional measurement of stars moving near the → zenith. The advantage is that there is no → atmospheric refraction occurring at the zenith. If a star on one night passes through the center of eyepiece, one must observe it six month later, and see if the star has been offset by the center. A shift would mean a measure of parallax. See also: → zenithal well.

zenith; → telescope

zenithal
  سرسویی   
sarsuyi

Fr.: zénithal   

Of or relating to the → zenith; located at or near the zenith.

zenith; → -al.

zenithal well
  چاه ِ سرسویی   
câh-e sarsuyi

Fr.: puit zénithal   

1) A well used in Antiquity from bottom of which the sky could be observed during the day with a better contrast. The aperture of the well reduced the light diffused by the sky.
2) A vertical tunnel in → Paris Observatory (built in 1667), from the top roof to the underground vaults, 55m deep. This well had the purpose of observing the stars near the → zenith and measure their → parallaxes. The problem was the lack of stability of the images so that the zenithal well was hardly used. See also: → zenith telescope.

zenithal; → well.