A planet is termed combust (burned) when it is in conjunction with the Sun and therefore hidden from sight by the light of the Sun. Traditionally this is a serious affliction and implies that the planet is weakened or restricted in power. It is often used to signify someone in fear or feeling overwhelmed, or to represent things that are kept hidden from sight.
William Lilly stated that the combust planet should be within 8° 30' – beyond this distance, but within 17° of the Sun, the planet is said to be under the Sun’s beams. This condition is debilitating, but not as severe as combustion.
More ancient authors generally used 15° to note the distance of being under the Sun's beams, and were less specific about the limits of combustion - generally, the expectation was that the closer the planets is to the Sun, the more intense and debilitating the effect is expected to be.