A little north-west of the star μ Leporis is Hind’s “crimson star” (R.A. 4h 53m, S. 14° 57′, 1900) described by him as “of the most intense crimson, resembling a blood drop on the background of the sky; as regards depth of colour, no other star visible in these latitudes could be compared with it.” It is variable from about the 6th to the 8th magnitude, with a period of about 436 days from maximum to maximum.
The constellation Canis Major, the Great Dog, is remarkable for containing Sirius, the brightest star in the heavens. In the Greek mythology it was supposed to represent a dog given by Aurora to Cephalus as the swiftest of all dogs. Cephalus wished to match it against a fox which he thought surpassed all animals for speed. They both ran for so long a time, so the story goes, that Jupiter rewarded the dog by placing it among the stars. But probably the dog comes from Anubis, the dog-headed god of the ancient Egyptians. According to Brown, Theogirius (B.C. 544) refers to the constellation of the Dog.[433] He thinks that Canis Major is probably “a reduplication” of Orion; Sirius and β Canis Majoris corresponding to α and γ Orionis; δ, 22, and ε Canis Majoris to the stars in Orion’s belt (δ, ε, and ζ Orionis); and η; and κ Canis Majoris with κ and β Orionis.[434]
The Arabic name of Sirius was al-schira, which might easily be corrupted into Sirius. The Hebrew name was Sihor. According to Plutarch, the Ethiopians paid regal honours to the Celestial Dog. The Romans used to sacrifice a dog in its honour at the fetes called Robigalia, which were held on the seventh day before the Calends of May, and nine days after the entry of the sun into Taurus. Pliny says, “Hoc tempus Varro determinat sole decimam partem Tauri obtinenti quod canis occidit, sidus per se vehemens,” etc.[435]
Owing to some remarks of Cicero, Horace, and Seneca, it has been supposed that in ancient times Sirius was of red colour. Seneca says, “Nec mirum est, si terra omnis generis et varia evaporatio est; quam in cœlo quoque non unus appareat color rerum, sed acrior sit Caniculæ rubor, Nartis remissior, Jovis nullus, in lucem puram nitore perducto.”[436] It is now brilliantly white with a bluish tinge. But this change of colour is somewhat doubtful. The remarks of the ancient writers may possibly refer to its great brilliancy rather than its colour. Al-Sufi says nothing about its colour, and it was probably a white star in his time. If it were red in his day he would most probably have mentioned the fact, as he does in the case of several red stars. Brown, however, quotes the following from Ibn Alraqqa, an Arabian observer:—
“I recognize Sirius shining red, whilst the morning is becoming white.
The night fading away, has risen and left him,
The night is not afraid to lose him, since he follows her.”
Schjellerup thinks that it is very doubtful that Sirius was really red as seen by Hipparchus and Ptolemy. But in an exhaustive inquiry made by Dr. See on the supposed change of colour,[437] he comes to the conclusion that Sirius was really red in ancient times. Seneca states distinctly that it was redder than Mars (see extract above), and other ancient writers refer to its red colour. It has been generally supposed that the Arabian astronomer Alfraganus, in his translation of Ptolemy’s Almagest, refers to only five red stars observed by Ptolemy, namely, Arcturus, Aldebaran, Betelgeuse, Antares, and Pollux. But Dr. See shows that this idea is due to a mistranslation of Alfraganus by Plato Tibertinus in 1537, and that Ptolemy did not speak of “five red stars,” but five nebulous stars, as stated by Christmann and Golius. Ptolemy described Sirius as ὑπόκιρρος, “fiery red,” the same word used with reference to the other stars mentioned above. The change of colour, if any, probably took place before Al-Sufi’s time.
Dr. See says—
“Prof. Newcomb rejects the former well-authenticated redness of Sirius, because he cannot explain the fact. But the ink was scarcely dry on his new book on the stars, in which he takes this position, when Nova Persei blazed forth in 1901; and observers saw it change colour from day to day and week to week. Could any one explain the cause of these numerous and conspicuous changes of colour? Shall we, then, deny the changes of colour in Nova Persei, some of which were noticed when it was nearly as bright as Sirius?”[438]
On the ceiling of the Memnonium at Thebes the heliacal rising of Sirius is represented under the form and name of Isis. The coincidence of this rising with the annual rising of the Nile is mentioned by Tibullus and Aclian. About 4000 B.C. the heliacal rising of Sirius coincided with the summer solstice (about June 21) and the beginning of the rising of the Nile. The festival in honour of this event was held by the Egyptians about July 20, and this marked the beginning of the sacred Egyptian year. On the summit of Mount Pelion in Thessaly there was a temple dedicated to Zeus, where sacrifices were offered at the rising of Sirius by men of rank who were chosen for the purpose by the priests and wore fresh sheepskins.
Sirius seems to have been worshipped by the ancient Egyptians under the name of Sothis, and it was regarded as the star of Isis and Osiris. The last name without the initial O very much resembles our modern name.