Rahu and Ketu are not bodies. There is nothing at either position — no rock, no light, nothing a telescope can find. They are the two points where the Moon’s orbit crosses the plane of the Earth’s orbit, and Vedic astrology treats those two intersections as planets with full standing in a chart.
Understanding what they physically are settles most of the questions people have about them, including why they are always opposite, why they always move backwards, and why published transit dates for them disagree.
The astronomy
The Moon’s orbit is tilted about five degrees to the ecliptic — the plane in which the Earth goes round the Sun. Two tilted planes crossing produce a line, and that line meets the sky at two opposite points. The point where the Moon crosses going north is the ascending node, Rahu. The point where it crosses going south is the descending node, Ketu.
Three consequences follow directly:
- They are always exactly 180 degrees apart, because they are the two ends of one line. No calculation can put them anywhere else.
- They move backwards. The nodal line precesses westwards, completing a circuit in about 18.6 years. This is why the nodes are described as permanently retrograde — it is not a periodic apparent motion like a planet’s, it is their actual direction of travel.
- Eclipses happen at the nodes. An eclipse requires the Sun, Moon and Earth in a line, which requires the Moon to be at or near a node when it is new or full. This is exactly the mythology: the severed figure that swallows the Sun and the Moon.
The 18.6-year cycle also means each node spends roughly eighteen months in a sign, which is why nodal transits are read as long structural periods rather than as weather.
Mean node and true node
This is the source of nearly every date disagreement, and it is worth knowing because it makes the disagreements comprehensible rather than suspicious.
The nodal line does not precess smoothly. The Sun’s gravity perturbs the Moon’s orbit, so the true node wobbles forward and backward around a smooth average. The mean node is that smooth average. The true node is the instantaneous position, which can sit up to about a degree and a half either side of the mean and occasionally moves briefly forward.
Classical Vedic practice uses the mean node, and most Indian panchangs follow it. Western sidereal software often defaults to the true node. A degree and a half of nodal motion is about a month, so two sources can honestly differ by several weeks on when Rahu changes sign.
Rahu occupies Aquarius and Ketu occupies Leo through almost all of 2026, having entered in 2025. They move to Capricorn and Cancer at the very end of the year — around late November by the true node, and around the first week of December by the mean node. If you see both dates quoted, that is why.
What the tradition assigns to them
Neither node rules a sign in the classical scheme, and neither has a fixed exaltation that all authorities agree on. What they have instead is a characteristic mode of operation, and the two are treated as opposites.
Rahu
Rahu is read as amplification without limit: appetite, ambition, foreignness, novelty, obsession, and the pursuit of worldly result. It takes on the character of whatever it sits with and magnifies the affairs of the house it occupies. The classical descriptions consistently pair its capacity to deliver material result with an equal capacity to leave the person unsatisfied by it.
Ketu
Ketu is read as the opposite motion: detachment, subtraction, and concentration into a single narrow channel. The house Ketu occupies is where the tradition expects both unusual facility and a lack of interest in the ordinary rewards of that department. Ketu is the node associated with what is already finished, and with skill that arrives without apparent effort.
Because they are one axis, a reading treats them together. Rahu’s house and Ketu’s house are always opposite, and the pair is read as a single tension between something the chart is reaching for and something it is letting go of.
Rahu Kaal is not about Rahu’s position
This causes more confusion than any other point, so it is worth separating cleanly.
Rahu Kaal is a fixed segment of the daylight period. The time between sunrise and sunset is divided into eight equal parts, and one of those parts is assigned to Rahu according to the weekday. It is arithmetic on sunrise and sunset, and the position of Rahu in the sky has no part in it whatsoever.
Rahu’s sign placement is a transit lasting eighteen months. Rahu Kaal is a window of ninety minutes or so that recurs every week on schedule. They share a name and nothing else.
The nodes in the dasha cycle
Both nodes hold full periods in the Vimshottari dasha system: Rahu 18 years and Ketu 7. Together that is 25 of the 120, so a fifth of the cycle belongs to two points that are not objects.
The Rahu mahadasha is the second longest in the system after Venus, and because it is read as the period of worldly reaching, it is often the stretch in which the outward shape of a life changes most. Ketu’s seven years are read as the counterpart — a period of narrowing, and often of ending things that the Rahu period built.
Nakshatras owned by the nodes
Each node owns three of the 27 nakshatras. Ketu owns Ashwini, Magha and Mula — the first nakshatra of each of the three rounds, and each one sits at the start of a fire sign. Rahu owns Ardra, Swati and Shatabhisha.
A Moon in one of these six at birth starts the dasha cycle in a nodal period, which is a distinctive beginning: the first years of life run under a point rather than a planet.
Common questions
Are Rahu and Ketu malefic?
Both are classed as malefic in the natural scheme, but the classification is less useful for them than for planets. Since they take on the character of their dispositor and of anything they conjoin, a node’s reading depends more on its surroundings than its own nature. The tradition also credits Rahu with some of the strongest material results in the system, which is not what a straightforwardly malefic reading would predict.
Can they be seen?
No. They are geometric points. What can be seen is their effect — an eclipse only occurs when the Moon is near one of them, which is how the ancient astronomers located and tracked them in the first place.
Why is Ketu given fewer years than Rahu?
The dasha lengths are the tradition’s own allocation and are not derived from anything astronomical. Ketu’s seven years match Mars’s, and Rahu’s eighteen sit between Mercury’s seventeen and Saturn’s nineteen. No classical source explains the arithmetic; the numbers are given rather than argued.
Do they aspect houses like planets?
Most practitioners give them the standard seventh aspect, and many follow the convention of giving them Jupiter’s fifth and ninth aspects as well. This is one of several points where practice varies, and a reading should state which convention it is using.
The astronomy described here is standard and checkable. The interpretations assigned to the nodes are the traditional readings of the classical literature, not predictions about events.
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