Combust planet (Asta)
A planet is combust (asta) when it sits so close to the Sun that it is lost in its glare. Astrologers read its significations as overshadowed or harder to express, though how much this matters varies by planet.
Also known as: combustion, astangata, moudhya
The Sun outshines anything near it, so the classical texts treat a planet within a set distance of the Sun as “set” (asta). The usual limits, from the Surya Siddhanta, are: Moon 12°, Mars 17°, Mercury 14° (12° when retrograde), Jupiter 11°, Venus 10° (8° when retrograde) and Saturn 15°. Rahu and Ketu are never combust.
A combust planet may struggle to show its qualities openly; a combust Mercury, for example, can make someone think more than they say. Many astrologers soften the rule for Mercury, which never strays far from the Sun and is combust in a great many charts. Mercury with the Sun also forms Budhaditya yoga.
Combustion matters for timing too. Weddings and other major ceremonies are traditionally avoided while Jupiter or Venus is combust, periods known as Guru asta and Shukra asta. In a birth chart it is one factor among many: dignity, house and aspects still count.