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

Of or near the → Sun, especially rising and setting with the Sun. → heliacal rising, → heliacal setting.

Heliacal "pertaining to the sun," from Gk. heliakos "of the sun," from helios, → sun; cognate with Pers. hur, as below.

Hurâné "sunlike," since the star rises in the morning like the Sun, from hur "sun", variant xor; Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun" + -âné similarity suffix.

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.

The last visible setting of a star below the western horizon just after sunset entering into a conjunction with the Sun.

→ heliacal; → setting.