Many ephemeris’ list solar and lunar eclipses. So it is easy to see that there are at least 2 a year, dependent on where the nodes are located. Each pair is at one of the nodes, so we can’t say that solar eclipses only occur where Ketu is placed and lunar eclipses where Rahu is placed. This reinforces looking at them as a split entity, in the singular mind you. They can’t be separated.
In the vedic tradition they are looked at as polar aspects of incarnation/excarnation. The sanskrit words used are moha; meaning such things as hallucination, infatuation, distraction, delusion, confusion, and moksha; meaning liberation, release from rebirth, redemption, deliverance. Moha has the root, muh (be crazed, stupefied, bewildered). Moksha has the root muc (to set free, release, deliver, draw off). You might ask yourself how the connection is made between Rahu/Ketu and moha/moksha and how the phenomena observed during solar and lunar eclipses fit into this. I’m going to attempt to fill in the gaps. We need a few more concepts and I think this will be easiest to present them in a table:
Without the Sun and Moon we can’t understand Rahu and Ketu and that is not only at the astronomical level. We need to contrast what the Sun and Moon represent and so need to introduce the concepts of atma (the spirit) and manas (the mind). Atma experienced as a quality not unlike light, intangible and illuminating and manas experienced as a quality of reflection, multiplying, manifoldness.
During the solar eclipse the Moon obscures the light of the Sun as seen from the earth. During the lunar eclipse the light reflected by the Moon is obscured by the earth. This is only possible during a new moon or a full moon taking place when Rahu and Ketu are present. They are associated with the shadow (they are after all called shadow planets). If we want to speak mythologically then we could say that Rahu is the shadow-giver and Ketu his counterpart reflects his shadow. According to the vedic tradition the only reason why we as human beings incarnate is because we desire the material world, we are under the influence of Rahu who gives us the delusion that the material world is the ‘real’ world, that the body that clothes us is the ‘real’ us. Ketu on the other hand forces us out of the body and as such releases us.
Now let’s look at the hushed mood of the solar eclipse described in the last post. If the eclipse were to last over weeks it would be like a drought of light, the strange twilight mood would be like dying so in a sense Ketu can be associated with the in-between time just as Rahu can be associated with the act of swallowing the Sun. Rahu gives the shadow and Ketu in a sense reflects his shadow. Rahu enacts the act of incarnation in that intangible light is swallowed, incorporated. Atma becomes ensheathed by the body, is swallowed. Ketu enacts the moment of dying, the hush, the loss of color, the loss of sense-perception.
A lunar eclipse shows another aspect of the pair. The dull orange color of the Moon can be seen as either the crazed sheen of Rahu’s eyes, lusting for the light of the Moon, but it can also be seen as his reflection, that is, Ketu trying to attach himself to the Moon. Ketu, being headless, would appropriate the reflective quality of the Moon, which is in a sense light in a more tangible form focused on its source, very much like incarnated atma exploring the manifoldness and multiplicity of light as manas. Ketu would envelop it in smokiness, liberate it from its focus, blur it.
You can see that by exploring the phenomena, with a little background philosophy, we can begin to approach some of the significations of Rahu/Ketu and see how they particularly apply to what can be termed the disruptive experience of incarnation/excarnation both from the physical standpoint (grasping for life/death of body) and psychological standpoint (delusion/death of mind).
I am sure there are Sanskrit scholars who could give a much deeper analysis of the root words used in atma, manas, moha and moksha and their interaction with one another, not to mention all of the related words that would expand on the very limited discussion presented above.