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

The rising of a star in the sky at or just after sunset. → heliacal rising.

→ acronical; → rising.

The instant of time when the object is in the East and the geometric → zenith distance is equal to 90° plus the → horizontal refraction plus the semidiameter minus the → parallax.

→ apparent; → rising.

The first appearance of a star following a period of invisibility due to its conjunction with the Sun. → heliacal rising of Sirius.

→ heliacal; → rising.

The first rising of → Sirius at dawn shortly before → sunrise. The heliacal rising of Sirius played a significant role in ancient Egypt by heralding the annual flooding of the Nile. The event took place some 70 days after the star had been seen for the last time in the western horizon at sunset. The heliacal rising of Sirius and its association with the rebirth of the Nile was so important that it marked the start of the Egyptian calendar year. At the time, the heliacal rising occurred in early July, as seen from the ancient capital of Memphis. But due to the → precession of the equinoxes the star now reappears in early August in Egypt. The date depends on the latitude (assuming transparent skies), being later for higher latitudes. For latitude 48° it occurs on about August 19.

→ heliacal; → rising; → Sirius.

A star that is never seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance larger than the altitude of the pole.

Nonrising, from → non- + rising adj. of → rise; → star.

Setâré, → star; hamiše penhân, literally "always hidden," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always" (Mid.Pers. hamêšag "always") + penhân "hidden."

The act of rising; the appearance of a celestial body above the horizon. Opposite of → setting.

Verbal noun of → rise.