Rahu Mahadasha, Mercury Antardasha (Rahu–Budh)

The Mercury antardasha is the fourth of the nine sub-periods inside the Rahu mahadasha. 18 × 17 ÷ 120 makes the Rahu–Mercury sub-period 2 years 6 months 18 days on the classical year of twelve thirty-day months, which is how the texts state it, or 931 days on the solar year of 365.2425 days that the dasha calculator uses.

Mercury’s turn in the Rahu mahadasha comes only after Rahu, Jupiter and Saturn have run, which takes 7 years 11 months 12 days. When the Rahu–Mercury sub-period gives way to Rahu–Ketu, 7 years 6 months of the Rahu mahadasha remains.

Mercury’s 17 years make every Mercury antardasha 17/120 of the mahadasha containing it, so inside Rahu’s 18 years the Rahu–Mercury sub-period is the fourth-longest of the nine.

The Nine Pratyantardashas of Rahu–Mercury

A pratyantardasha of Rahu–Mercury is 18 × 17 × its own lord’s years ÷ 14,400, and the nine run in cycle order starting from Mercury. Venus’s is the longest inside Rahu–Mercury at 153 days and the Sun’s the shortest at 46 days, on the classical year and rounded to the day.

How Rahu and Mercury Stand to Each Other

Rahu’s row in the friendship lists counts Mercury a friend. Mercury’s row names no node, so the other direction of the Rahu–Mercury relationship has no entry, and this page does not supply one. The nodes have no row in the seven-graha table that kundli matching uses; the node’s own entry is the one printed on its planet page.

Rahu owns no sign in the standard scheme, so the Rahu–Mercury sub-period has no fixed distance between lordships. What stands in for it is the node’s dispositor — the lord of the sign Rahu occupies at birth — which differs from chart to chart.

The Same Pair the Other Way Round: Mercury–Rahu

18 × 17 equals 17 × 18, so the Rahu antardasha of the Mercury mahadasha is exactly as long as Rahu–Mercury: 2 years 6 months 18 days. Nothing else about Mercury–Rahu matches. It is the seventh sub-period of Mercury’s 17 years rather than the fourth of Rahu’s 18; it opens after 9 years 5 months 27 days of the Mercury mahadasha, against 7 years 11 months 12 days here; and its pratyantars start from Rahu instead of Mercury.

What the Texts Assign to Rahu and Mercury

The karaka list the tables give Rahu, the mahadasha lord, is foreign lands and foreigners, technology, aviation and politics; for Mercury, the lord of the Rahu–Mercury sub-period, it is speech, writing, trade, accounts, mathematics, maternal uncles and students. Parashari practice reads the sub-period through the houses each of the two owns and occupies in the birth chart (for Rahu, which owns none, the house it occupies and the lord of its sign), and through where Mercury stands counted from Rahu there. None of that is a forecast, and this page makes none: without a chart, Rahu–Mercury is a length and a position, and the 2 years 6 months 18 days above is the whole of what can be said about it in general.

A birth with the Moon in Ardra, Swati or Shatabhisha opens life inside the Rahu mahadasha itself, part-way through, and whether the Rahu–Mercury sub-period is still ahead depends on how far the Moon had gone into the nakshatra. For a birth in Ashlesha, Jyeshtha or Revati, the Mercury mahadasha comes first, and the Rahu mahadasha is the seventh in that sequence.

The Other Sub-Periods of the Rahu Mahadasha

The full table for the Rahu mahadasha, with where each sub-period opens and closes, is on the Rahu mahadasha page. How the Rahu mahadasha is read as a whole is in our Rahu mahadasha article, and the system itself in Vimshottari dasha explained. This page in Hindi: राहु महादशा में बुध अंतर्दशा.