Saturday, August 6, 2011

Sirius heliacal rise

We recently published a post detailing the mechanics of the heliacal rising of a star or constellation. The heliacal rising of Sirius is currently taking place (on days that vary slightly depending upon your latitude on the earth) -- an extremely important event in ancient civilization.

For observers at about 35° north latitude and an elevation at sea level, Sirius rises on August 7th at 5:32 am. It continues to rise about four minutes earlier each day, a phenomenon described in this previous post.

At the same latitude and elevation, the sun rises on August 7th at 6:16 am. It continues to rise about a minute later each day (in the northern hemisphere), as the earth proceeds along its orbital path from the summer solstice (which already took place back in June) towards fall equinox (in September) and ultimately to winter solstice.

Until its heliacal rise, the sun was rising earlier than Sirius. However, as Sirius rises earlier and earlier, it eventually begins to rise earlier than the sun (and as it keeps rising earlier and earlier its rise will continue "into the night" and further ahead of sunrise). When Sirius first begins to rise earlier than the sun, the sky is still too bright to observe Sirius. However, as Sirius continues to rise earlier, it is higher in the sky each day when the sun comes up. Another way of thinking about this is that the sun is lower and lower below the eastern horizon as Sirius comes up over the eastern horizon each morning (because Sirius is rising earlier and earlier). Eventually, Sirius will rise prior to the sun at such a point that the sky is not bright enough to drown it out, and Sirius will be visible in the early morning sky above the eastern horizon, which will be lit by the sun's rays but not enough to drown out this brightest of fixed stars. When Sirius rises above the horizon and the sun is still 7° below the horizon, Sirius will be bright enough to be seen.

Fainter stars than Sirius must continue rising earlier before they are seen on their dates of heliacal rise, meaning that the sun would have to be further below the horizon than 7° before they would be visible for the first time. However, Sirius can be seen when it rises far enough ahead of the sun to crest the horizon when the sun is still 7° below the horizon. These conditions are beginning to be met for Sirius this week (on August 7th in most of the latitudes of the continental United States).

In their seminal text Hamlet's Mill: An Essay on Myth and the Frame of Time, Giorgio de Santillana and Hertha von Dechend discuss the incredible importance of the star Sirius to ancient civilizations -- including the ancient advanced civilization that they believed must have predated Sumer, Babylon and dynastic Egypt, and bequeathed to them a highly sophisticated understanding of astronomy, mathematics and science.

They point out that Sirius was associated with a plethora of ancient mythological images and themes. In addition to being the star of Isis the consort of Osiris, Sirius was also identified (among other things) with a celestial bow and arrow (216). De Santillana and von Dechend show that ancient Babylonian star descriptions identified the stars that we associate with the lower legs and tail of the constellation Canis Major with a drawn bow pointing to Sirius, which became the "Arrow Star."

The constellation is shown below, with the positions of the stars that form the bow pointing to Sirius connected by bright green lines:

That this bow pointing to Sirius was very ancient is confirmed by its depiction in ancient Egyptian imagery, such as the Round Zodiac at Dendera (see detail below):

The great emperors of Ancient China were also depicted pointing the bow and arrow at a celestial dog or jackal, clearly indicative of the Dog Star Sirius, as shown in the image below (a similar image is reproduced in Hamlet's Mill between pages 216 and 217, as is the Dendera Zodiac shown above):

The authors of Hamlet's Mill explain that Sirius was also associated in some way with the depths of the sea, citing for example an ancient Babylonian New Year's ritual addressed to the "Arrow Star, who measures the depths of the sea" and the sacred texts of Zoroastrianism, the Avesta, which names the arrow Tishtriya and addresses it as "Tishtriya, by whom the waters count" (358). They also cite also numerous myths in which a goddess or a maiden who shoot an arrow from a bow into the midst of the ocean -- or to "the navel of the ocean" -- including a myth from the Northwest Indians of British Columbia (318).

In his book Sirius Matters, astronomer Dr. Noah Brosch notes that in the past, "the heliacal rising of Sirius was an outstandingly favorable time for the gathering of medicinal herbs" (26). He also records that in the time of the ancient Greeks, the men of the island of Kea (Ceos) in the Aegean each year "would dress up in armor and ascend a hill to witness the heliacal rising of Sirius" (25).

If possible, be sure to rise early this week and look for the brilliant star Sirius before the sunrise, low in sky by the eastern horizon. Look for Orion and use the belt, drawing a line through the belt stars towards the horizon. The image at the top of this post shows Orion and Sirius to the left of the belt stars -- in the morning, when Orion is just rising, the constellation will be oriented more horizontally than pictured above (to orient the picture above the way you will see it in the sky before dawn, just mentally rotate the image above counterclockwise almost a quarter turn, for viewers in the northern hemisphere).