The ancient Egyptian New Year began when the spectacularly brilliant star Sopdet (Sothis in Greek; Sirius in Latin) was seen to rise before the sun in the early morning. This is known as the heliacal rising of the star. During part of the year, you see, Sirius is so close to the sun that the greater solar light blots out the light of the star and the star seems to disappear from the sky. The heliacal rising is the day that the sun and Sirius are once more far enough apart that—for the first time in months—Sirius may be once again seen in the pre-dawn skies. From at least the time of the Pyramid Texts, the beautiful star Sopdet was associated with the beautiful Goddess Isis. Sirius is the holy star of Isis and you can look for Her heliacal rising sometime this month.
To the ancient Egyptians, the rising of Sirius was the herald of the all-important Nile flood, as well as marking the beginning of the year, Thoth 1. Yet the five days just before the heliacal rising of Sirius were important, too. The Egyptian civil calendar (there were a variety of calendars in ancient Egypt) divided the year into 12 months of 30 days each. That, of course, only adds up to 360 days, and the year is 365 (plus a bit, which is why we still need a “leap year” today) days long. The Egyptians knew this, too, so in order to bring the civil year into harmony with the solar year, they added five “days upon the year” or epigominal days to the calendar. On these magical days that were outside of normal time, the Egyptians celebrated the birthdays of Osiris, Horus the Great, Set, Isis, and Nephthys. Plutarch preserved this tradition for us in his essay, On Isis and Osiris, and the divine birthdays are also marked on the ancient Egyptian calendar known today as the Cairo Calendar.
You can see why Isis devotees would want to know when Sirius rises; so that we may celebrate the Birthday of our Goddess in the traditions of the ancient calendar.
So precisely when does Sirius’ heliacal rising occur? Well, it depends on where and when you are located in the world and in time. The further north of the equator you are, the later in the year you will see Sirius rise; and due to the precession of the equinoxes, the date of the star’s rising shifts over time. You will likely be able to see the rise of Sirius sometime this month; exactly when depends on exactly where you are.
You might think it would be relatively easy to find out when such an important star as Sirius rises locally. It isn’t. When I was writing Isis Magic, I even called my local planetarium and they weren’t able to help me. I scoured the internet. I inquired on Egyptian and astronomy lists and forums. But no luck. That was then; this is now. And I am happy to say that I have since found an online calculator—and I’m going to share it with you.
It was designed by a French doctor of astronomy with an interest in ancient Egypt. She offers software for purchase that lets you calculate any star’s heliacal rising. But here’s the good part: you can sample the calculator—on Sirius—for free. Here’s the link. (Put in your email and the password softtests) All you need to know is your latitude and altitude (how much above sea level) and be able to put up with the Google Translate version of the site—unless you speak French, of course.
To find Sirius in the night sky, just look for the constellation Orion, which was associated with Osiris by the ancient Egyptians. The three stars in Orion’s belt point directly at Sirius.