Dog days sometimes used for the lethargic summer markets. Various computations of the dog days have placed their start anywhere from 3 July to 15 August and lasting for anywhere from 30 to 61 days. They may begin or end with the cosmical rising or heliacal rising of either Sirius in Canis Major or Procyon (the "Little Dog Star") in Canis Minor and vary by latitude, not even being visible throughout much of the Southern Hemisphere. Sirius observes a period of almost exactly 365¼ days between risings, keeping it largely consistent with the Julian but not the Gregorian calendar; nonetheless, its dates
The Sirius Mystery that the Dogon considered Sirius to be a double star and/or that astronomy was particularly important in their belief system. Others, such as Marcel Griaule's daughter Geneviève Calame-Griaule and an anthropologist, Luc de Heusch, came to criticize Van Beek's dismissal as "political" and riddled with "unchecked speculation", demonstrating a general ignorance of Dogon esoteric tradition. In 1978, Astronomer Ian Ridpath observed, in an article in the "Skeptical Inquirer", "The whole Dogon legend of Sirius and its companions is riddled with ambiguities, contradictions, and downright errors, at least if we try to interpret it literally." Ridpath stated that while the information