Were Rahu and Ketu considered true planets in ancient times?

  • History
  • Thread starter Ad VanderVen
  • Start date
  • Tags
    Planets
In summary: Instead of that most ancient cultures I know about traditionally just went with the most obviously visible (Sun, Moon) and the stars : some of them weirdly agile (Mercury, Venus, Mars, Jupiter, Saturn) and some stationary (constellations)Since the Hindu astrology added those two, you can be sure they took them as real 'points of interest': they found that something is happening there, so there must be something/somebody responsible, clear targets for inventions of colourful imagination.
  • #1
169
13
TL;DR Summary: Were Rahu and Ketu considered true planets in ancient times before 500 AD and is there any evidence for this in the ancient scriptures?

Nowadays when people ask what Rahu and Ketu are, it is always said that those names refer to the lunar nodes. Now I thought that that interpretation only arose after the appearance of the Aryabhatiyam in about 500 AD, written by Aryabhata. I thought Aryabhata even emphasizes in the Aryabhatiyam that Rahu and Ketu are not true planets (or celstial bodies), but I'm not sure. But if Aryabhata has said that, then in his time and also before that there was apparently the idea that Rahu and Ketu were real planets or celestial bodies. My question now is whether there is any evidence for this in the scriptures before the Aryabhatiyam.
 
Last edited:
Science news on Phys.org
  • #2
Ad VanderVen said:
My question now is whether there is any evidence for this in the scriptures before the Aryabhatiyam.
How is that a physics question? Shouldn't you be asking a theologian?
 
  • #3
Vanadium 50 said:
How is that a physics question? Shouldn't you be asking a theologian?
This is a physics question! I ask if there is any written evidence for the idea that scholars in ancient India thought that Rahu and Ketu were real planets or at least celestial bodies. I need this information in connection with an article I am writing about a certain period in the history of astronomy (not astrology).
 
  • #4
The question you are asking is historical, or theological, or astrological or something. "What did people write down" is not physics. It's history (or theologym or astrology, or....)

A physics question would if there is any evidence of two additional planets in historical times. The answer to that us "no".
 
  • #5
It's possible there is someone here who is that into the history/theology of astronomy from the eastern side, but unlikely. We can wait and see.
 
  • #6
Vanadium 50 said:
The question you are asking is historical, or theological, or astrological or something. "What did people write down" is not physics. It's history (or theologym or astrology, or....)

A physics question would if there is any evidence of two additional planets in historical times. The answer to that us "no".
It is indeed not physics, but it is very important to the history of physics. For example, what Galileo Galilei wrote about astronomy is important for the knowledge of the history of astronomy. Unfortunately, there is no section on the history of astronomy on PhysicsForums. That's why I have to ask the question in this section.

If you don't know the answer to my question, I'd really appreciate it if you stopped getting involved in this discussion.
 
  • #7
russ_watters said:
It's possible there is someone here who is that into the history/theology of astronomy f
We do have a history section. Perhaps that is a better spot for it,
We don't, of course, have a theology section.
 
  • Like
Likes russ_watters
  • #8
Vanadium 50 said:
"What did people write down" is not physics.
Indeed it is not physics, but it is very important for the history of physics. For example, what Galileo Galilei wrote aboot astronomy is imporatfor the jhsistpry of astronomt
Vanadium 50 said:
We do have a history section. Perhaps that is a better spot for it,
We don't, of course, have a theology section.
Please, can you give me the web address of the history section? I couldn't find it on PhysicsForums.
 
  • Like
Likes russ_watters
  • #10
(thread has been moved)
 
  • Like
Likes Vanadium 50
  • #11
Ad VanderVen said:
if there is any written evidence for the idea that scholars in ancient India thought that Rahu and Ketu were real planets or at least celestial bodies.
A bit of an opinion here: it is kind of hard to come up with a (modern-ish) definition of 'real planet' without a telescope and some kind of not totally weird model of the solar system.

Instead of that most ancient cultures I know about traditionally just went with the most obviously visible (Sun, Moon) and the stars : some of them weirdly agile (Mercury, Venus, Mars, Jupiter, Saturn) and some stationary (constellations)
Since the Hindu astrology added those two, you can be sure they took them as real 'points of interest': they found that something is happening there, so there must be something/somebody responsible, clear targets for inventions of colourful imagination.

But even their other 'planets' are not real planets.

To be aware of the difference in definitions and avoiding the forceful matching of two identically looking words with different meaning in different contexts is not physical, but a very linguistics thing.
 
Last edited:
  • #12
Has the OP considered comparing historical sightings of periodic comets and meteor showers within the time period of the ancient texts under study?

If memory serves, physics professor Robert Oppenheimer and colleagues at UC Berkeley attempted to reconcile certain Vedic and other Sanskrit textual references to celestial objects with historical sightings of (periodic) comets. IMS astronomical records from ancient China among other sources provided confirmatory data of comets and meteor showers potentially visible to scholars on the subcontinent.

As an example of this concept, consider the historical sightings of Halley's comet enshrined in the Bayeux Tapestry. More specifically to Sanskrit texts, I understood Hindu references to Rahu and Ketu could refer to supposed patterns in the Earth-Moon system used to calculate relevant eclipses of Sun, Earth, Moon and other known celestial objects including propitious alignments of same, along with periodic meteor showers. This begs the question whether 5th/6th Century astronomers realized periodic meteor showers might be remnants of old comets?

Imagine the chagrin of a court astronomer who predicts some propitious appearance of, say, Mars and Jupiter in conjunction in order for their patron to schedule some royal event, only to have the calculated sighting obscured or overshadowed by other celestial objects.

260px-Comete_Tapisserie_Bayeux.jpg
 
Last edited:
  • #13
Maybe this paper can help answer some questions.

Pre Telescopic Astronomy - Invisible Planets Rahu and Ketu
Chapman-Rietschi, P. A. L.
Quarterly Journal of the Royal Astronomical Society, Vol. 32, NO.1/MAR, P. 53, 1991
https://adsabs.harvard.edu/full/1991QJRAS..32...53C
 
  • #14
Sure, I had read that article a long time ago, but it didn't help answer my question at all.
 
Back
Top