Background The definition of jyotiSaa in brhat samhita is a person who has multi-dimensional knowlege and makes use of this knowledge to do predictive modelling and make predictions out of them. Since it is not possible for one person to do it all, brhat Samhita calls for a team of jyotisaa to work together and make predictions for a King. Simply put, jyotiSa is a science of predictive modelling with data from various information sources and using that model to make reasonable inferences about the future. Like it or not, it is just like economics (1). This is all about information becoming knowledge to make reasonable inferences for future, which are approximations, but which keeps on becoming better and better. A person practising jyotiSa can neither claim to make accurate predictions nor can allow the instincts to over-run the inferences. I had also described the 'luminaries' that have pround impact on planet Earth and they are visible even to our naked eye (2).