Rahu joined Jupiter is called Guru Chandala yoga. Rahu tends to interrupt Jupiter much in the way that Ketu tends to interrupt Mercury because Rahu is about variety, trying new things and taking experience through making mistakes. It is not about listening, following instructions or teachings and believing in things.
Rahu / Ketu and Jupiter
This is good with Mercury because Mercury is about the same thing. But Jupiter is about the power of our experience to be a great teacher and to believe and learn from life. Life is a great teacher and those things that we believe in—not necessarily religion—are great sources of strength to us.
Rahu is not about believing in things, it is about trying new things. So it is called Guru Chandala yoga because it interrupts that faith-inspired quality of Jupiter.
Ketu/Jupiter is actually quite conducive because Ketu is also about faith. It is about the belief in what we have experienced already. Ketu is about the past and this idea that we understand and know something already. That can be very disruptive to certain areas of life like for instance, the present moment where we need to be flexible, creative and open to new experience which is Mercury stuff. Ketu/Mercury is kind of interrupting.
Jupiter is actually the belief in the power of what we have learned and how that can prevent us from making the same mistakes over and over again. That is what wisdom is about, it is about belief. But it is always in what you have learned already and what you have experienced. That is Ketu stuff. Ketu is about the past and what we have been through and it can get sort of calcified around this certainty that is very rigid. With Ketu it is quite rigid, but with Jupiter it is not, it is quite expansive.
Ketu joined Jupiter is going to interrupt Jupiter to some extent but it is also going to really concentrate the energy of Jupiter. It can interrupt in the sense of making us maybe a little bit rigid, dogmatic, religious and even somewhat atheistic which sound like a contradiction but it is not because atheism is also a kind of a religion.