Why the name "eclipse"
Rahu and Ketu are the lunar nodes — the two points where the Moon's orbit crosses the Sun's path. A solar or lunar eclipse can only happen when the Sun and Moon are near these points. In the Puranic image, Rahu (the demon's head) and Ketu (its body) swallow the luminaries in revenge for being exposed at the churning of the ocean. So when a birth chart places the Sun or Moon right beside a node, astrologers call it Grahan dosh — the light is, symbolically, partly eclipsed.
The two forms
Surya grahan dosh — Sun with Rahu or Ketu
The Sun stands for the soul, self-confidence, the father, authority and government. With Rahu, the reading is ego confusion, conflict with father or bosses, and reputation problems; with Ketu, a weakened sense of self and detachment. Sun–Rahu is also one of the main indicators of Pitru dosh.
Chandra grahan dosh — Moon with Rahu or Ketu
The Moon is the mind, emotions, the mother and peace at home. With Rahu: anxiety, overthinking, fears and restlessness; with Ketu: emotional withdrawal and a feeling of emptiness. This is usually considered the more troubling of the two, because the Moon governs the mind.
How strong it is
- Closeness matters: a luminary within a few degrees of the node is much more affected than one at the other end of the sign.
- Dignity matters: an exalted or own-sign Sun or Moon (Sun in Aries or Leo, Moon in Taurus or Cancer) resists it far better.
- Aspects: Jupiter's aspect is the classic protection.
- Birth during an eclipse: many consider a birth on an actual eclipse day — when the luminary and node are exactly together — the strongest form.
Remedies
For the Sun
- Surya arghya at sunrise every day.
- The Aditya Hridaya Stotra — the hymn the sage Agastya taught Shri Ram on the battlefield — on Sundays, and the Surya Gayatri Mantra.
- Respect and service to one's father. See Sunday Surya bhakti.
For the Moon
- Monday worship of Shiva, who wears the Moon on his head — jalabhishek with milk and water, and Om Namah Shivaya.
- The Mahamrityunjaya Mantra for steadiness of mind.
- Care for one's mother, and charity of rice, milk or white cloth on Mondays.
For both
- Japa, charity and bathing during actual eclipses — the traditional time to "answer" the eclipse.
- Navagraha Stotra and Rahu–Ketu shanti, for example at Sri Kalahasti.
A balanced note
Sun–Rahu or Moon–Ketu conjunctions are common, and many people with them lead calm, successful lives. When the Moon is involved and anxiety is a real, daily struggle, mantra and prayer help — and so does talking to a doctor. Both together are wiser than either alone.