Ruchaka is one of the five Pancha Mahapurusha yogas, the great-person combinations of jyotisha. Each of the five forms when one of the five non-luminous classical planets, Mars, Mercury, Jupiter, Venus, or Saturn, occupies its own sign or its sign of exaltation while standing in a kendra, an angular house (the first, fourth, seventh, or tenth) from the ascendant. Ruchaka is the yoga of Mars, formed when Mars is so placed. The tradition reads it as conferring the martial virtues in strength: courage, physical vigour, leadership in war or command, discipline, and a commanding presence, giving a person of the warrior type. These are the interpretive conventions of the tradition; the yoga is a defined placement of Mars in dignity and angularity, and its promised results are held to depend on the planet remaining unafflicted.
Brihat Parashara Hora Shastra, the classical source for the five, defines the condition purely from the ascendant, but later authorities do not all agree on that limit. Mantreswara, in the sixteenth century Phaladeepika, holds that Ruchaka and the other four Mahapurusha yogas can be reckoned from the natal Moon as well as from the ascendant, and are effective when formed from either point, with the strongest form arising when the placement holds from both simultaneously, which he says can raise the native to the rank of a sovereign. Parashara's own text does not concur with this extension, and modern commentators including B. V. Raman follow Parashara in restricting the yoga to the ascendant alone, so a chart satisfying the condition only from the Moon is read as bearing the yoga by one authority and as lacking it by another.