When is the actual transit of Rahu/Ketu?

[gansub]

According to this site - https://www.drikpanchang.com/planet/tra ... -time.html

today one transit of Rahu and Ketu took place. Then another one takes place on March 23rd. For prediction purposes when is the exact day of transit ? And what is the difference between the two transit dates?

[justicetomeplease]

dear gunsub, True nodes have wobbling motion where as mean nodes doesn't. As per BPHS, sage has clearly mentioned to consider equal house division. So, the motion of nodes should also be uniform to fit the zodiacal plane. Hence we mean nodes only. That's what is been suggested. These true nodes can go in a direct motion as well, but where as mean nodes will always retrograde.
So, today mean nodes are transiting. On 23rd of March the true nodes are transiting. So, as per the results are concerned many of the Vedic Astrologers considers nodal transit from today afternoon itself. As they consider mean nodes.
regards

[vedicmaths]

Hello gansub

My humble opinion on the question raised by you.

With varying standards in the value of ayanamsas, true or mean nodes, the difference in transit of the
nodes does not really matter for any astrologer. The boundaries of the zodiacs too are debatable.

truly yours,
vedicmaths

[gansub]

Hello Vedicmaths,
Thanks for your prompt response. Sorry if I cannot follow what you have written. If I understood you correctly you are saying it does not matter if Rahu/Ketu are transiting into Gemini/Sagittarius or not. I think beyond a certain day all ayanamshas would agree a particular planet is in a particular sign. GIven that principle when can I assume that they have moved ? Or are you saying we should not worry whether they move or not?

[ChandraLagna]

@justicetomeplease: Parashara has not mentioned equal house division in BPHS, and secondly it is not relevant in the context of true/mean nodes. When the motion of earth and moon are not uniform, how can the derived points of nodes be uniform? You say "we" mean (mean) nodes. Who's we? There are enough astrologers that consider true nodes. So, there is nothing to decide with any degree of finality. v=u+at is a theoretical physics equation where you find uniform velocity and acceleration, its rare to find it in real world.

I concur with Vedicmaths - there are so many varying factors including Ayanamsa that have impact on when the nodes actually move. Just changing Lahiri to another ayanamsa changes the date of crossover.

Gansub - to answer your query, beyond March 23, nodes do appear to have changed signs at least for the commonly used Ayanamsas. One outlier is Raman Ayanamsa that seems to indicate April 4th, but while this is less used, yet some astrologers do use it.

[justicetomeplease]

I thought equal house division is needed for mean nodes to use, as everything will be equal in proportion, speed at every instant (degree per day) will be constant. That's why.
BPHS did mention equal house division
The verse goes like this:
तत् द्वादशविभागास्तु तुल्या मेषादिसंज्ञकाः|
प्रसिद्धा राशयः सन्ति ग्रहस्त्वर्कादिसंज्ञकाः||
That Meshadisanjnaka's which are 12 parts which are tulya (meaning balanced) or equal.
It's mentioned right?
...
Dear, When in a smooth system (where there's less friction) if a block is displaced the equation which you've mentioned still holds good!

[ChandraLagna]

Many things wrong in above paras, so let me point them out methodically.
1. Firstly, that verse does not talk about houses, just signs. As I have pointed out in the other thread, a house is not the same as a sign. A house can span multiple signs.
2. Next, houses or signs has nothing to do with mean nodes or true nodes or even equal proportionality. You could have equal houses and unequal velocities, or vice versa. Merely dividing zodiac into 12 parts does not make the nodes assume uniform motion. The nodes are mathematical points which depend on motions of earth and moon and if the motions of these two planets are not uniform, what makes us believe nodes have uniform motion? The mean motion is merely a statistical convenience. I can divide a distance of 100 meters into equal parts of 10 meters each and run each 10 meter segment with different velocity.
3. Ayanamsa has a big impact on the actual transit days and when there are so many Ayanamsas, there is no guarantee of any one being correct. It's all a matter of opinion, experience and bias if you will.
4. You have to be more accurate than that for a Physics student ! No....that equation only works when the friction is Zero, not merely "less". It assumes many things - uniform acceleration, zero friction and linear motion without effects of other bodies or even gravity and none of these assumptions hold good in real life, not in the heavens.

[justicetomeplease]

On point 4
On a horizontal plane what's the point of gravity at all? Gravity is redundant in the above equation...Yes that equation valid only when the motion is uniform acceleration. a=dv/dt is the correct equation. It's the definition of acceleration & it's valid every time. That above equation was derived from this.
On point 1
The verse spoke about Mesha Ādi Sanjñakās, when it said Mesha ādi, so it's talking about Rāsi's so signs as you said. If signs are equal in proportion wherever you consider the bhava's starting point the bhava length should be same. Or do you mean a bhava can have more than 30°? When it's said all signs (Rasi) should be equal in size?

[ChandraLagna]

Why assume a horizontal plane? Secondly, gravity is not just a force the earth exerts. Force of attraction exists between all bodies that have mass. Yes, a=dv/dt and that equation recognizes that acceleration is instantaneous, can change next instant, and if applied to nodes, makes them wobbly. This just proves my point to consider instantaneous values and not the average values.
On houses/signs, it is irrelevant to current discussion, since as I explained above one can have equal divisions and unequal speeds. We have discussed the bhavas/signs enough in different thread.

[justicetomeplease]

Dear CL, a small correction we shouldn't say that if a is applied to nodes, makes them wobbly. It's wobbling that's why we consider instantaneous acceleration.
thanks & regards.

[ChandraLagna]

No. We only realize it is wobbling after we measure instantaneous acceleration and see that there is variation across different "dt"s. In general we do not want to make assumptions about the nature of a body's motion till we measure its motion and it's only then we can understand whether its linear, uniform, or non-uniform etc.

IN fact, even retrogression does not mean that a planet is moving in opposite direction to its real or original motion. It simply means that the relative motion has changed and thus "appears" to be moving back, or stationary depending on the change.

There are many areas of astrology that are contentious, and there is no shame in admitting that we do not know or understand many things.

Hopefully this digression helped a casual reader, but the OP has her answer from VedicMaths and my earlier post above.

[justicetomeplease]

A small typo, read as It's wobbling that's because of instantaneous acceleration. Not as that's why we consider. (Didn't see the statement)
Of course I admit that I'm an amateur in Astrology & learning.

[ChandraLagna]

Now the horse and cart are in the right order!