the heliacal rising

The heliacal rising refers to the first appearance of a star or planet in the dawn sky just before sunrise, after it has been obscured by the Sun’s light for a period. This phenomenon occurs due to the Earth’s rotation and orbit around the Sun. For example, the heliacal rising of Sirius, the brightest star, marked the start of the flooding season in ancient Egypt, signaling important agricultural events. Historically, these occurrences were crucial for calendars, navigation, and timing agricultural practices, serving as guideposts for various cultures throughout history.