As a subject, Jyotiṣa has several major branches, including:
- Lakṣaṇa Śāstra – the study of bodily features, signs, and omens in the surroundings. This includes palmistry (hasta-rekhā śāstra), which is associated with Subrahmaṇya or Kārtikeya.
- Hora Śāstra – the domain of Gaṇeśa.
- Gaṇita Śāstra – mathematics, including Vedic numerology, is another major branch.
All these come under the three divisions: Gaṇita, Hora, and Saṁhitā.
Once, a debate (śāstrārtha) took place between Kārtikeya and Gaṇeśa, with Lord Śiva as the judge. Kārtikeya composed the entire Lakṣaṇa Śāstra, while Gaṇeśa composed Hora Śāstra. Śiva declared Hora superior to Aṅga-Lakṣaṇa (which includes palmistry and the study of bodily features). Angered by this, Kārtikeya threw his entire book into the ocean. Later, it was partially recovered by various teachers. Hence, palmistry is also called Sāmudrika Śāstra—the knowledge obtained from the ocean. The term Sāmudrika may also imply that which encompasses all gestures and expressions.
For Praśna (horary astrology), one must study Aṅga-Lakṣaṇa thoroughly and also develop skill in it, along with the study of omens (śakuna), which form part of Saṁhitā (Nimitta Śāstra). Therefore, anyone wishing to learn this must worship Kārtikeya; otherwise, it is not possible to master the subject—just as Hora Śāstra becomes very difficult without Gaṇeśa. These deities are the original authors of these sciences, and only they can truly impart their knowledge.
Additionally, Jyotiṣa is governed by the Grīṣma (summer) season, one of the six Vedic seasons, which is ruled by Mars (Maṅgala). Therefore, worship of a form of Mars is essential for this study. In our tradition, Narasimha sādhana is recommended for this purpose. You are also taught Gaṇeśa sādhana.
When we teach the Praśna course, we will also cover the worship of Kārtikeya in the form of Subrahmaṇya and study the Praśna Upaniṣad. In this Upaniṣad, Kārtikeya is regarded as the teacher, and Maharṣi Pippalāda as the disciple.
With reverence.
May you be wise ~ Namaskar
