May 28, 2017

Sirius B and the Curious Case of the Dogon.

The ever-controversial star Sirius. (Photo by Author).

Every beginning astronomy student learns that Sirius is the brightest star in the sky. This brightness is apparent, as Sirius is a spectral type A1V star located relatively close to our solar system at about 8.6 light years away. Much myth and lore surrounds this star, but none is stranger that the mythology of the Dogon people. Incorporated into the mythos of these people that inhabit the plains of Mali is a bizarre tale of Sirius, which they call Sigi Tolo. They claim that the star has a small unseen companion in a 50 year orbit that they call Po Tolo. This companion star is tiny but dense, so dense that all the men in the world could not lift it. The mystery deepens as they also go on to claim that Jupiter has four large moons, and that Saturn has a ring “like that seen sometimes around the Moon, but different…” All of these claims are basically true. Sirius has a companion star, a white dwarf known as Sirius B discovered in 1862 by Alvan Graham Clark. This star is made up of degenerate matter, making it extremely dense, about 1×109 per kg/m^3. And the knowledge of Jupiter and Saturn has been around since Galileo first turned his crude telescope to the heavens…

The Dogon People…

(Credit: Martha de Jong Lantink’s Flickr photostream on a Creative Commons 2.0 License).

So, what’s going on here? Why would an isolated tribe have knowledge that technology only revealed to western eyes in the past few centuries? A quick search around the Internet of the Dogon and Sirius reveals no shortage of theories involving ancient alien contact. The modern pedigree of this tale can be traced back to a 1976 book by Robert Temple entitled The Sirius Mystery. Remember, the 1970’s was a time when Eric von Daniken and his Chariots of the Gods was in vogue, and archeologists were seeing space-helmeted aliens everywhere. Temple based much of his book on the writings of anthropologist Marcel Griaule, who spent time with the Dogon off and on from 1931 to 1956. And much of that particular legend comes from an interview with local Dogon wise man Ogotemmeli. You get the picture. Further research with the Dogon has revealed either no trace of the legend or discrepancies with the tale. For example, they also state that there is a third star in the Sirius system they call Emme ya Tolo, which is the opposite of Po Tolo in that it is both “big and light” but no other star has yet to have been found. Also, as with any sole source, it’s tough to say how much bias there may have been on the part of the recorder… it’s easy to lead a subject, even subconsciously, to the data that we might want to hear. In addition, some confusion exists on whether Ogotemmeli was referring to Sirius or the bright planet Venus in reciting the tale.

The orbit of Sirius B. (Adapted from Burnham’s Celestial Handbook).

In 1979, Carl Sagan proposed that the information might have been given to the Dogon by an external source, albeit a terrestrial one. Keep in mind, the legend coming to light in the 20th century wasn’t really giving us any new information about Sirius; psychics perform this feat all the time when they claim to have predicted events that have already happened. When we look at ancient myths and lore, we need to be mindful of the creativity of the human mind; after all, what would archaeologists thousands of years from now make of a Star Trek episode? That we somehow had warp drive and phaser technology? A true myth having some sort of predictive power would be far more compelling. Does this mean that the discovery of a red dwarf star around Sirius, as was spuriously reported in the 1990’s, would lend some credence to the tale? While interesting, I don’t necessarily believe so, as red/brown dwarf stars are quite common in the cosmos; for example, it’s not totally ruled out that our own sun may have a dim unseen companion!

Like white dwarfs, red dwarfs are common throughout the cosmos. (Credit: NASA/H. Bond).

What Sagan proposed is that the knowledge was passed on by a visiting explorer in the late 19th century, and incorporated into the Dogon mythos by the time Griaule did her interview. The image is compelling; an explorer eager to tell the “primitives” about the triumph of western science, imparting new information to the Dogon about their honored star. Keep in mind, another ancient African people, the Egyptians, based their calendar on the Sothic cycle and the helical rising of the star Sirius. Perhaps, said explorer had a telescope on hand to show them Jupiter and Saturn for good measure.

The original Dogon Sirius diagram. (Credit: Bad Archaeology).

But do any historical expeditions fit the bill? Well, there was in fact a total solar eclipse that passed over the region of modern day Mali on April 16th, 1893, and several expeditions were indeed in the area; these expeditions would have been well-equipped with astronomical gear and astronomy and curiosity about the heavens would have been on the forefront of everyone’s minds. And yes, Saturn had just passed opposition and Jupiter would have been an early evening target in the months leading up to that date.

Jupiter at dusk in April 1893. (Created by the Author in Starry Night).

And the diagram purported to be centuries old? Well, keep in mind that it only bears a passing resemblance to an elliptical orbit; it looks a lot like an egg, which symbolizes re-birth and is prevalent in the mythos of many cultures (witness the “Easter eggs” of western culture; a throwback to pure paganism!) The original diagram sketched out by Ogotemmeli shows several other curious objects within the egg; later commentators have edited them out making the case for Sirius B to seem more conclusive than it really is. And keep in mind that we see the orbit of a binary star system generally tipped to our line of sight between either edge-on and face on; it would relatively easy to find several “matches” to the Dogon diagram in the sky.

The total solar eclipse of 1893. (Credit: Fred Espenak, NASA/GSFC).

While I think the Dogon case is more interesting than most, I don’t find it compelling as a sign of ancient extra-terrestrial contact. Keep in mind, this is still giving us knowledge that we already knew; exacting knowledge, such as a chant that encoded how to build a functioning hyper-drive, for instance, would be much more inexplicable and compelling. The final fact often cited is that the Dogon believe in a heliocentric, or Sun-centered solar system, a fact that took us centuries of denial to realize. In this case, I believe that the Dogon should be recognized as astute observers of the sky; anyone can arrive at this conclusion as the Greeks initially did by merely studying the naked eye motions of the heavens and not allowing pre-conceived notions of how the world should be to cloud their judgment. All too often, we fail to give credit to the ingenuity of ancient cultures where credit is due. These people knew the sky far better than the average citizen does today and relied on it as a natural clock. Perhaps such intimate knowledge of peoples like the Dogon should be viewed for what it really is, rather than attributed as merely given to them from afar.

AstroEvent: Herschel 3945-A Clone of Albireo.


A “pretty pair…” (Photo by Author). 

Probably the most famous star party doubles are Alcor & Mizar in the Big Dipper and Albireo in Cygnus. Both provide a good, wide separation, and in the case of Albireo, a good color contrast. Plus, double stars provide a good “punch through” of the light pollution haze for down-town astronomy, and may save the show when the Moon or planets aren’t above the horizon and even the best nebulae such as M42 evoke remarks like “what, you mean that fuzzy smudge?” [Read more...]

AstroEvent(s): Of Occultations & Daytime Stars.

Mekbuda Occultation from Tampa, Florida. (Created by Author in Starry Night). 

This week brings with it an interesting double-double header. First up is a challenge that comes to us via the Royal Astronomical Society of Canada … sure, you’ve seen Venus near the daytime Moon, and perhaps you’ve caught Jupiter low at opposition just prior to the setting of the Sun… but did you know that it’s possible to catch some of the brightest stars while the Sun is still above the horizon? Right around the first full week of April is a good time to give this a try; your assigned quarry is Sirius in the pre-dusk, and Vega in the post-dawn. Both of these stars are in the negative magnitude range and might just be visible from a pristine site with good seeing. In the case of Vega, a fun project would be to acquire it before sunrise and follow it into the daytime skies either visually or with an equatorial tracking telescope. Sirius, although brighter at magnitude -1.5 may be tougher; in this instance, finding the star in relation to a nearby landmark a day prior at dusk and then trying to acquire it before local sunset may work. I once successfully caught Jupiter in the daytime in this fashion, near opposition from the arming-end of runaway in Kuwait back in 1998. Good luck, and we’ll be attempting this feat of visual athletics right along with you!

But wait, there’s more… this week also sees the waxing crescent Moon pass through some interesting star fields in the constellations Taurus and Gemini. The result is a series of interesting stellar occultations; 1st, on the evening of April 7th, the Moon skims the Hyades cluster and occults Upsilon and Kappa Tauri for viewers in western North America. Kappa is of particular interest as it is a very close (0.1”) double. Even if you aren’t in the target zone, the crescent Moon+Hyades= a good photo op. Three days later, we US east coasters get a shot with an occultation of Zeta Geminorum, otherwise known as Mekbuda. This is another bright star around magnitude +4.0. Mekbuda is also a Cepheid variable with a period of 10.2 days, one of the brightest in the sky. Watching this star wink out and then reappear should be a good replay of last month’s Mu Geminorum occultation… the action for the US East Coast centers around ingress at 9:21 PM EDT and an egress of 10:35PM. The occultation extends up to a graze line cutting across the Canadian Maritimes… good luck, and watch this space for a video after-action clip if successful!      

The astro-term for this week is Transparency. In terms of astronomy, transparency is the ability for light to pass unhindered through the atmosphere. Pollution, dust, and aerosols all act to scatter light and dim objects. You can have clear skies, but poor, washed out transparency. Generally, the higher and drier you are, the better transparency will be, as evidenced by a deep blue daytime sky and an inky black nighttime sky. This is also an all important factor in success in daytime star-spotting as discussed above.  Transparency is rated 1 to 10, with 10 being the absolute best, and is closely tied with seeing, or the resolution ability based on atmospheric turbulence. I’ve had clear skies and decent transparency after a storm front, only to have poor seeing as the convective cells rolled before my eyepiece!   

Astro Event of the Week: The Heliacal Rising of Sirius.

Sirius Rising as seen from Astroguyz HQ on August 1st, at Lat. 28 North...Radio Telescopes pending! (Created in Starry night).

Sirius Rising as seen from Astroguyz HQ on August 1st, at Lat. 28 North...Radio Telescopes pending! (Created in Starry night).


   August is traditionally a real roaster for the northern hemisphere. This month usually sees the onset of what’s known as the Dog Days of summer… but did you know that this term has an actual astronomical tie-in? We’re talking about the dawn appearance of the Dog Star, Sirius.  The ancient Egyptians knew this star as the dog-headed god Anubis, and the first sightings of Sirius preceded that most important of calendar dates in their world; the flooding of the life-giving Nile. [Read more...]

August 2010: Life in the Astro-Blogosphere.

 Summer Lightning as seen from Astroguyz HQ. (Photo by Author).

   Summer lightning as seen from Astroguyz HQ. (Photo by Author). 

   The sultry days of summer are now upon us, in what’s usually the last of the traditional northern hemisphere summer months. You can almost feel the darkness beginning its slow creep back into our daily lives. Although we continue to operate in “stripped down mode” new Astroguyz content will  still continue to be generated on a bi-weekly basis. Here’s what you can expect coming to an astro-blog near you; [Read more...]

Astro-Event of the Week: Can You Spy Sirius B?

(Constructed by the Author in Paint).

(Constructed by the Author in Paint).

The elongated orbit of Sirius B.

   This week’s challenge is a tough one, and may deserve a re-visit or two over the coming decade  to yield success. Everyone knows that Sirius is this brightest star in the sky, but did you know that it has a tiny, elusive white dwarf companion? Tough to locate, this +8.7 magnitude object currently lies at an apparent separation of 9” arc seconds and growing. Usually, that wouldn’t be a tough split, except for the fact that bright Sirius A swamps it out by its -1.42 magnitude brightness! To spot it, you’ll need a telescope of at least 4” aperture, high magnification, and clear, pristine skies. Also, an eyepiece equipped with an occulting bar could prove helpful; the trick is to cover up the bright primary to the northeast while Sirius B lies to the left at a south western position angle. [Read more...]

AstroEvent of the Week: February 2nd-8th, 2009; Spot a Daytime Venus!

A Daytime Venus Shortly After Occultation. (Video by Author).

Astronomy isn’t just restricted to a night time activity. Many folks do not realize that objects such as the Moon can be spotted even in broad daylight. This week, I give you a fun daytime naked eye challenge; spotting Venus in the daytime.  No special equipment is required; just a sharp set of eyes and persistence. [Read more...]

Astro Event of the Week: 24-30 June, 2008

Moon & Pleiades.

(The Moon Occulting the Pleiades M45 Open Cluster, about 3AM EDT.  Credit: Stellarium)

Early morning risers next Monday are in for a treat; a rare occultation of the star cluster, the Pleiades, by the Moon. [Read more...]

Astrology: An Astronomical Perspective

Astronomy may well be man’s oldest scientific endeavour. When we weren’t busy eking out an existence, we were looking to the stars. The sky to our ancestors must have seemed enigmatic and mysterious. Removed from terrestrial affairs, the heavens seemed aloof. [Read more...]