Thursday, October 14, 2021

Orion and Friends



It's 5:30AM and there is a nip in the air. You look out from the balcony and your gaze moves up from the empty roads, the streetlights, over the tree-tops, to one single bright star in the sky.

Which one is it? you wonder..

As your eyes get accustomed to the darkness, other less bright stars peek out through the haze, and a familiar pattern emerges - the three stars that make the belt, two for the dagger, another two pairs each for the shoulders and limbs... and Orion the Hunter emerges in all its glory. Then again on either side of the hunter two more bright stars - Aldebaran and Sirius marking the positions staked by the constellations Taurus and Canis Major.


We are now the Navaratri festival season, a period of nine nights when the moon transforms from a thin sliver barely visible in evening sky, to a bright autumn full-moon marking, not only two of the most important festivals in India, Dussehra and Diwali, but also the onset of winter.

I often wonder - why are our night skies filled with stellar patterns that carry mostly Latin names, with a few Arabic ones thrown in for variety? What did the ancients in India, South America or Australia make of these patterns in the night sky?

As Raj Vedam explains so well in his videos, ancient astronomers in India looked at the skies in a very different way, with oral traditions that record and mark the changing positions of the moon, planets and stars with almost obsessive detail. So much so that with modern software simulations it is possible to triangulate the time-period of certain historical events that could only have happened thousands of years ago. 

The Ecliptic, or the path taken by the sun to traverse the sky, is one of the key reference points. They observed that - "The moon appears on the eastern horizon at a different time every day, offset by about 48 minutes, agains a different backdrop of stars." Also, it was noticed that it takes 28 days for the moon to return to the same backdrop of stars. From this emerged a system based on Nakshatras and Raashis.

Nakshatra refers to the principal or brightest star in each segment of the night sky, formed by dividing the ecliptic into 27 segments of 13.33 degrees (13.3 * 27 = 360). As a mnemonic to remember the right sequence these stars were woven into mythology to represent 27 wives of the moon.

Similarly the 12 lunar months were made by dividing the sky into 12 segments of 30 degrees each (12 * 30 = 360), represented by the constellation in which the full moon made its appearance. These were called the Raashis.

So when the full moon appeared in Chittira Nakshatra (Spica in Virgo Constellation) it could immediately be understood that in that month, the sunrise took place 180 degrees opposite in Ashvini Nakshatra (Sheratan or Beta Arietis in the Aries constellation).

What about old familiar friend Orion and his companions? For some reason it seems ancient astronomers in India were not too keen on conjuring up figures from the stellar patterns. They highlighted only three stars in the Orion and Taurus constellations:

One big surprise is that in the subsequent 13.3 degree segment they completely ignored the brightest star in the sky, Sirius and instead selected Pollux (Gemini constellation) as Nakshatra no. 7. To put this in perspective, Pollux  or Beta Geminorium is an orange giant with a magnitude (brightness) of 1.1 while Sirius (Greek for 'scorching' and also called Alpha Canis Majoris) has a magnitude of - 1.5 which is about 2.5 times brighter!

Maybe there is something more to this that I am missing, but ignoring the brightest star in the sky! - you can't be Sirius! 

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REFERENCES & LINKS

* Orion Constellation - ultimate guide - https://www.planetguide.net/orion-constellation/

https://www.astrosoftware.com/SiriusNakshatra.htm

* Inca Astronomy - https://www.peruforless.com/blog/inca-astronomy/


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