Rahu and Ketu have been termed as shadow planets. Every shadow is formed by a real object. What are the real objects whose shadows Rahu and Ketu represent?
It is not an object that forms the shadow of Rahu Ketu but it is the fact that Rahu and Ketu are shadows formed which are always consistent as a mathematical entity. Let us first understand this with an example:
Suppose you have a torch pointing at a wall in front of you. Now, if you keep a ball in front of the torch, the ball will appear as a shadow on the wall, right? If the ball moves, the shadow moves. Hence, it is the ball which is the object casting the shadow. The ball is the shadow and the shadow is the ball. Only on different planes of existence. One is a reflection, other is a material.
In such a case, you do not need to define the shadow as an object. As long as you known about the ball, you can precisely know about the shadow. The shadow is just a residue of the torch and the ball.
On the other hand, let us say that there is no ball in front of the torch. But then I go and put up a blue ball in front of the torch. Now there is again a shadow formed. But then I remove the red ball and now place a green ball in front of the torch. Again, the shadow appears. Now I put up a blue ball, and then a pink one. Shadow again and again.
So, is the shadow of the blue ball? Or the green one? Or the green one?
Or can I say that the shadow is a fixed point on the ball that would appear each time I put an object in its front? Thus, irrespective of a specific object, the moment something obstructs the torch, shadow will appear.
Now, let us replace the torch with the Sun. Let us replace the ball with Earth and let us put a smaller ball (Moon) revolving around the bigger ball (Earth).
So now, if the Moon is between Earth and Sun, a shadow will fall on Earth and we would not be able to get the light of Sun. The obstruction is because of Moon and the result is the absence of sunlight.
Again, if the Earth is between Sun and Moon, we on Earth would not be able to see the Moon because Sun's light would not reach Moon. Here, the obstruction is now Earth not moon bit the result is absense of Sunlight.
The object causing the shadow has changed, but the point is that the light of either of the luminaries is getting obstructed because the three are in direct path of each other. If moon’s light is obstructed, it is a lunar eclipse. If Sun’s light is obstructed, it is solar eclipse.
It is for this reason, that Rahu Ketu is an axis and not a point. It is a straight on which IF the sun, the moon and the earth are placed together, an eclipse would form. And it is for this reason that they move backwards.
So you see, in the above depiction, as earth moves in one direction, Rahu and Ketu move in the other.
Now, observe the fact that Rahu and Ketu are an infinite axis. they are not a point. Rahu and Ketu is the line joining the three collinear entities which are the Earth, the Sun and the Moon. If I look up, I can only say that there in the sky if the Moon comes, it would form an eclipse. It is the line that creates shadow when all three are there, it is NOT an object or a single point. It is a perceived point that I can point in the sky. But I cannot say that Rahu-Ketu exists at 1000 Km in that direction. Rahu and Ketu are a phenomenon and not an entity. They are a direction and a line, not an object or a point.
Now, this is the very reason for defining Rahu and Ketu. If I were to calculate eclipses, I would need to know the exact position of both the sun and the moon. Now, the sun and the moon are not always on the same plane. Their paths are skewed as we call it. Which means, their paths is something like this.
Hence, either I need to know the angle at which Moon is going to be, along with the position of Sun and Moon; or I can simply locate the line known as the Rahu-Ketu axis and simply say that by definition Rahu-Ketu axis is the point where the Sun and Moon come on the same plane and form an eclipse.
Hence, Rahu and Ketu are not shadows of one particular object but the points where a shadow will form given any obstruction to sunlight (be it Moon or Earth).
Now, Interestingly, if you see that Rahu and Ketu are the points where the Earth’s orbit around Sun and the Moon’s Axis around the Earth intersect. In mythology you would know of the story of how the Asura Svarbhanu was cut into two by Vishnu and how Shiva granted them the boon to keep eclipsing Sun and Moon from time to time.
The beauty of it is that the path of the Moon around Earth keeps shifting. NASA claims that it has shifted some 6 degrees over 1 billion years. Hence, we can assume that once upon a time it would have been possible that the Sun and Moon came in a straight line only once. Which means, there would not have been two eclipse points in the ancient days of Earth but only one.
The Hindu mythology or Vedic literature talks in poetic verses and creates story out of Science. What you know as Vishnu’s Sudarshan is actually the earth’s orbit around Sun. The Sun, which in astrology represents Vishnu, Soul, Parabrahma is at its centre from where Vishnu holds the Sudarshan. Its motion creates life because that is how the Earth revolves around Sun and seasons are formed.
Swarbhanu, who was once a single demon, was the phenomenon of Eclipse that happened only once in a year and not twice. But with time, as Moon’s path shifted, the Earth’s orbit (Sudarshan) cut the Moon’s Orbit (Swarbhanu) into two hence forming the straight line of Rahu-Ketu axis which exlipses the Sun and the Moon today!
