The fourth month includes 20 July, the date of the heliacal rising of Sirius. A heliacal year is the interval between the heliacal risings of a star. The Sothic year is the interval between heliacal risings of the star Sirius. Harkhebi predicted the weather patterns of the heliacal risings of the fixed stars. The Dresden Codex contains a Venus table which records the heliacal risings of Venus. Three specific observations of the heliacal rise of Sirius are extremely important for Egyptian chronology. Depending on the observer's latitude many stars are subject to annual heliacal risings and settings. When a planet has a heliacal rising, there is a conjunction with the Sun beforehand. Thus the heliacal rising of Sirius marked the annual flooding of the Nile. For the Maya, the heliacal rising of Venus was associated with destruction and upheaval.