---
type: Concept
bundle: jyotisha-kala
bundle_version: 0.12.0
id: rahu-ketu
title: Rāhu-Ketu
iast: Rāhu-Ketu
devanagari: राहु-केतु
description: 'The ascending and descending nodes of the Moon’s orbit, the two shadow-grahas (chāyā-graha) at which eclipses occur; NOT a Sun-swallowing demon, NOT physical bodies, NOT karmic-point content.'
darshana:
- Jyotiṣa
text_source: Sūrya Siddhānta 4; Bṛhat Saṃhitā 5
tags:
- rahu
- ketu
- nodes
- eclipse
- jyotisha
not:
- term: 'a Sun-swallowing demon'
  why: 'The Svarbhānu/Rāhu narrative is the Purāṇic register. The siddhāntas compute eclipses geometrically from the nodes, where the Moon’s tilted orbit crosses the ecliptic, and Varāhamihira in the Bṛhat Saṃhitā explicitly discusses eclipse causation against the demon story. Quoting the myth as the tradition’s astronomy erases its astronomers.'
  instead: 'Render Rāhu and Ketu as the lunar nodes, the shadow-grahas, and keep the Sanskrit terms.'
- term: 'physical bodies'
  why: 'The nodes are mathematical points on the ecliptic, regressing through the zodiac in about 18.6 years. Jyotiṣa counts them as grahas by function while classing them chāyā-graha, shadow-seizers, precisely because no body sits there.'
- term: 'karmic-point content'
  why: 'Modern copy sells Rāhu-Ketu as universal karmic axes of desire and detachment. Those are interpretive significations from horā, not the definition; the definition is orbital geometry.'
related:
- /concepts/graha.md
- /concepts/rashi.md
timestamp: '2026-07-09'
okf_version: '0.2'
license: CC BY-SA 4.0
---

# Rāhu-Ketu -- राहु-केतु

**Not:** a Sun-swallowing demon, physical bodies, karmic-point content

## What It Actually Means

The Moon’s orbit is tilted about five degrees to the ecliptic; the two points where the paths cross are the ascending node (Rāhu) and descending node (Ketu). Eclipses occur only when Sun and Moon stand near a node, which is why the tradition classes the nodes among the nine grahas: nothing shines there, but the calendar of eclipses lives there. The siddhāntas compute the nodes’ retrograde cycle of about 18.6 years and devote chapters to eclipse computation from them, a fact that sits beside, and corrects, the Purāṇic story of the severed demon. Chāyā-graha, shadow-seizer, is the tradition’s own label for their bodiless status.

## Audience Metaphor

Two crossing-points where the Moon’s tilted track cuts the Sun’s road: nothing stands there, but when both travelers reach one together, the light goes out. The myth posts a demon at the crossing; the siddhānta posts coordinates and an 18.6-year timetable.

## Citations

1. Sūrya Siddhānta 4 on lunar eclipse computation from the nodes -- see [references/surya-siddhanta.md](../references/surya-siddhanta.md)
2. Bṛhat Saṃhitā 5 (Rāhu-cāra) weighing eclipse causation against the demon narrative -- see [references/brihat-samhita.md](../references/brihat-samhita.md)
