2024: Sirius’ heliacal rising occurs at different dates across the northern hemisphere. Look for the star in the southeastern sky before sunrise.
By Jeffrey L. Hunt
Sirius Heliacal Rising
Summer’s mid-point occurs near the time of Sirius’ first morning appearance or heliacal rising.
Despite the description by some writers, Sirius is not especially bright at the heliacal rising. It appears through the beautiful colors of mid-twilight in the east-southeast, slowly fading from view as twilight brightens. The following mornings, the star is higher in the sky and easier to locate at the same time interval before sunrise.
For sky watchers, the actual sighting of the celestial event is important, not just predicting when the event occurs. The theoretical date of the first appearance can be calculated, the visual sighting is compounded by weather and local geography.
Sirius’ heliacal rising gathers the most interest for the readers of these articles and its connection with Egyptian calendars. Sirius is sometimes known as the Nile Star as its first appearance occurred at the time of the annual rainy season that flooded the river to start the agricultural season.
2024 Helical Rising Dates
For 2024, the following table, based on astronomer Jean Meeus’ equations, shows the predicted heliacal rising for Sirius for selected northern hemisphere latitudes.
| Latitude (North) | Date |
| 10° | July 17 |
| 20° | July 24 |
| 30° | August 1 |
| 40° | August 10 |
| 41.85° (Chicago) | August 12 |
| 50° | August 20 |
| 60° | September 2 |
Begin looking for it at 50 minutes before sunrise a day or two before the predicted date. Use a binocular as necessary. The heliacal rising occurs on the first day the star can be seen without the binocular.
Sirius is part of an informal pattern known as the Winter Triangle, including Procyon and Betelgeuse. The shape is nearly an equilateral triangle. Finding Betelgeuse and Procyon shows the triangle’s scale and helps locate Sirius.
From Southern Hemisphere
It should be noted that for southern hemisphere sky watchers, Sirius is still in the evening sky during late fall and early winter. Like the familiar Arcturus, Vega, and Capella in the northern hemisphere, Sirius stays in the sky for long periods when viewed south of the equator. Sirius is still in the western evening sky when it makes its first morning appearance.
From 30° south latitude, Sirius first appears on June 22nd, while it continues as an evening body until July 11 when it is lost in evening twilight.
A Messy Calendar
Some writers and emailers state that for ancestral Egyptians, Sirius’ first appearance began a new year and they make absolute statements on the date. This is oversimplified. The Egyptian calendars were complicated and changed across time. What follows here is a quick look at the calendar. I encourage those who want to learn more to dig into the experts’ studies of the ancient Egyptian calendar.
Some records (source) indicate that the new rulers started a year on the first day they came to power. A citizen might only see one or two kings during a lifetime, so the calendar might be reasonably consistent.
During Egyptian dynasties, Sirius’ heliacal rising occurred during the rainy season in the Lower Nile River. (Remember that the river flows from south to north.) It helped signal the beginning of an agricultural cycle.
Civil Calendar
Two calendars were in effect. One was 365 days long, without a leap year. Assuming Sirius marked the beginning of the new year, the civil servants apparently knew about the need for a leap year, but they did not apply it. Without a leap day, the rising Sirius begins to slip in the calendar one day every four years. The beginning of the new civil year soon did not coincide with the date of the first appearance. Today, if leap year is not applied, seasonal festivals do not match with the traditional months. In the northern hemisphere, the months that we know as the cold months – December, January, and February – would occur during the hot times of the year.
Without leap years the entire cycle resets Sirus’ heliacal rising to the date of the new year in 1,460 years. The civil servants had to track this difference in their records, an odd practice, since they apparently knew that the civil calendar could be corrected by adding a day every four years. When writers simplify that Sirius’ first appearance started the Egyptian new year, it is a simplistic statement. Sure, maybe at times, but not always.
Agricultural Calendar
The second calendar used the moon’s lunation, that is easily recognized by everybody. To account for the moon’s cycle that is 29.5 days long, months were 30 days, with three seasons – inundation (or rainy), winter (or growing), summer (or harvest). Five days were added to extend the year to 365 days (source). The month began on the day following the last appearance of the waning crescent moon. Festivals occurred at various months and the related offerings to the gods were specified. This worked for an agrarian society. The calendar was reset easily with the appearance of Sirius so that the seasons of flooding, planting, and harvesting were consistent with the weather patterns. The new year started at the beginning of the next month after the heliacal rising.
Sky watchers recognized an annual cycle based on the sun and stars that was 365 days long. While the lunar cycle was used by the larger population, the civil calendar, based on the summer solstice and the zenith passage of the sun, was used by the civil servants, but the sun did not appear directly overhead for all of the kingdom. Another avenue was needed to begin the year.
A Revision?
When the Ptolemys came to power about 305 BCE, they attempted to align the culture to Greek practices and decreed a leap day that was not implemented. Sirius’ heliacal rising was proclaimed to occur on the 271st day of the year. So, at some point Sirius did not open new years, especially when a new ruler could declare when a new year began. It seems, though, that the calendar based on lunar phases, restarted at the next new moon following Sirius’ heliacal rising, was the consistent mode of keeping track of the years’ passings.
This year, attempt to view Sirius at its heliacal rising. During morning twilight, venture to a spot with a clear horizon to search for the star’s first morning appearance at your home latitude.
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Thank you so much for sharing this research! I was looking for information on Sirius and the concept of “Lion’s Gate” last year and found your 2023 article. I’m grateful that you have a 2024 version as well! I’ll make sure to refer you when I speak of this!
Hi, Thanks for reading the articles.
You’re welcome! Actually I have a question about the conjunction between the Sun and Sirius. I read in the Farmers Almanac that that happens on July 23. But that doesn’t sound right to me. I then also saw someone mention July 3. Can you say something about this? Thank you!
From what I can calculate, the sun and Sirius share the same celestial longitude on July 5th, but it’s hardly a conjunction as we might think of a pairing of Venus and the crescent moon. The sun and Sirius are about 40 degrees apart, since the star is that far from the ecliptic – the plane of the solar system. On July 23, they rise about an hour apart. Not sure of the F.A. reference, but somebody could be misquoting the “date” of Sirius’ heliacal rising on ancient calendars. These absolute dates that I’ve seen published are crazy speculation and somewhat nonsensical, especially when considering that those ancestral calendars did not use a leap day, making the date of heliacal rising float in the calendar and a Pharoh could declare the beginning of a new year at his whim. The agricultural calendar was reset to the beginning of the next month after the appearance of the star. This year, Sirius rises near sunrise – known as the Cosmic Rising – on August 3rd from Chicago’s latitude. There’s about a minute of difference in the rising times, but this is the date when the rising times are nearly the same. Many writers confuse the cosmic rising with the heliacal rising and the conjunction. Just go outside and look for it. Start looking for it a day or so before the calculated dates. Weather and topography greatly affect the star’s visibility. Thanks for the question.
Thank you for the clarification! This is so helpful. It seems to be that people are hanging on to absolute dates for some kind of comfort… maybe for clickbait as well. F.A. has articles each year about the Dog Days of Summer and this is how this date came up. And apparently the Dog Days of Summer end on August 11. 😉 Who knows! I’m just grateful to have found someone who simply follows the stars. Is there anyone else that you recommend I follow on this topic?
Based on my astrological research, I also found that the conjunction was on July 5. However, I was skeptical because I believe astronomers and astrologers use different diagrams to study the movements of the planets.
Do you feel (web site edited) is a good resource for those of us who don’t have a telescope but are fascinated by planetary movements?
Thank you so much for your time and help!
It is important for us not to apply the precision of today’s ideas with the cultural events of the past.
There are many people who write about sky watching on the internet.
There’s no difference in calculations when the celestial (ecliptic) longitudes are considered. Some sky watchers measure conjunctions along the celestial equator. Sirius and the sun have the same right ascension, angle along the celestial equator, on July 2, and this may be listed as a conjunction date in some sources. I use ecliptic coordinates because this is where the planets move. The conjunction in celestial longitude occurs a few days later. Conjunctions along the ecliptic are usually closer than conjunctions referenced to the celestial equator, although the equatorial coordinate conjunctions are not incorrect, just different dates.
Charts that show the geocentric positions are pretty useless (please excuse the word) for sky watching. They do not show the background stars, which make the planets’ motions interesting to watch. Further they do not usually display rising and setting times. There are plenty of planetarium programs, free and for purchase, that show the background stars with the planets.
Hello
Many thanks for this amazing article. I was wondering What the date is for 2024 of the heliac rising of Sirius from Louxor ? I have been having a hard time getting an answer
My 2025 estimate for Sirius’ heliacal rising for 2025 at Luxor, Egypt is July 28. This is the theoretical date and the actual sighting depends on weather and obstacles at the horizon.