Lunar Eclipse in Hinduism: Chandra Grahan

A lunar eclipse, Chandra Grahan (चंद्र ग्रहण), occurs on a full moon night (Purnima) when the Earth passes between the Sun and the Moon, casting its shadow on the Moon's bright face. In Hindu cosmology, this is the moment when Rahu or Ketu (the shadowy lunar nodes) are said to "swallow" Chandra, causing the Moon to darken and eventually turn a coppery red. This "Blood Moon" is the most dramatic celestial event in popular astrology.

The ancient text Surya Siddhanta and the Aryabhatiya describe lunar eclipse mechanics with precision comparable to modern calculations. Aryabhata (5th century CE) correctly identified that eclipses are caused by the Moon entering Earth's shadow, a rational astronomical explanation given centuries before the Western scientific mainstream reached the same conclusion.

Types of Lunar Eclipses

• Total Lunar Eclipse (Khagras Chandragrahana): The entire Moon enters Earth's umbral shadow. The Moon turns red/copper (Blood Moon) because Earth's atmosphere refracts sunlight around its limb, bending long-wavelength red light onto the Moon. Full Sutaka and Daan obligations apply.
• Partial Lunar Eclipse (Khandagras Chandragrahana): Only part of the Moon enters the umbra. A dark "bite" appears on the Moon's edge. Sutaka applies where partial eclipse is visible.
• Penumbral Lunar Eclipse: The Moon passes only through Earth's penumbra (outer shadow). The darkening is subtle and barely visible. Many dharmashastra texts do not require Sutaka for a purely penumbral eclipse.

Chandragrahana and Astrological Significance

The Moon (Chandra) governs the mind (manas), emotions, fertility, water bodies, and one's mother in Jyotisha (Vedic astrology). An eclipse of the Moon is therefore considered a particularly potent (and in some respects inauspicious) event for matters related to these domains. Eclipses occurring in a person's natal Moon nakshatra or the nakshatra of a major dasha lord are considered significant in Parashari Jyotisha.

Safe Viewing

Unlike a solar eclipse, a lunar eclipse is completely safe to view with the naked eye throughout its duration: no special filters are required. The Moon reflects only sunlight and emits no harmful radiation even at maximum totality. In fact, Total Lunar Eclipses are among the most breathtaking naked-eye celestial events visible from anywhere on the night side of Earth.

यस्मिन् पक्षे यत्र काले येन दृग्गणितैक्यम् ।
दृश्यते तेन पक्षेण कुर्यात्तिथ्यादिनिर्णयम् ॥

yasmin pakṣe yatra kāle yena dṛggaṇita-aikyam | dṛśyate tena pakṣeṇa kuryāt tithyādi-nirṇayam ||

"In whichever school and at whatever time the unity of observation and computation is seen: by that school alone should one determine tithi and all panchanga elements."

महाऋषि वशिष्ठ · Mahāṛṣi Vasiṣṭha

यात्रा विवाहोत्सव जातकादौ खेटैः स्फुटैरेव फलस्फुटत्वम् ।
स्यात् प्रोच्यते तेन नमश्चराणां स्फुटक्रिया दृग्गणितैक्यकृद्या ॥

yātrā vivāhotsava jātakādau kheṭaiḥ sphuṭaireva phala-sphuṭatvam | syāt procyate tena namaś carāṇāṃ sphuṭa-kriyā dṛg-gaṇita-aikya-kṛd yā ||

"In journeys, marriages, festivals and horoscopes: accurate results arise only from accurate planetary positions. Therefore the procedure that achieves unity of observation and computation (dṛg-gaṇita-aikya) is here declared."

Siddhānta Śiromaṇi · Bhāskarāchārya (1150 CE)

दृक्करणैक्य विहीनाः खेटाः स्थूला न कर्मणामर्हाः ।

dṛk-karaṇa-aikya-vihīnāḥ kheṭāḥ sthūlā na karmaṇām arhāḥ

"Planetary positions lacking the unity of observation and computation are crude and unfit for ritual actions."

Bījopanayana Bhāṣya · Siddhānta Śiromaṇi tradition