We’ve all been asked: why do people celebrate Diwali? The answers are many. It is the festival of lights. It is the night Rāma returns to Ayodhyā after exile and the defeat of Rāvaṇa. It is Naraka Chaturdaśī, when Kṛṣṇa, with Satyabhāmā, overcomes Narakāsura. It is Lakṣmī Pūjā, the welcoming of abundance. It is Kālarātri, the dark night of the Goddess in her fierce form.
Across India, Nepal (where it is celebrated as Tihar), Sri Lanka, and the wider South Asian world and diaspora, the festival is understood as the triumph of light over darkness. Jains remember the nirvāṇa of Mahāvīra on this night. Sikhs observe Bandi Chhor Divas. Beneath all these stories sits a shared cosmic setting, and that setting is the sky itself.
The Jyotiṣa of Diwali
Diwali (or Dīpāvalī) is observed on the new moon night (Amāvasyā) in the month of Kārtika, according to the pūrṇimānta (full moon to full moon counted) luni-solar calendar of North India. In the amānta (new moon to new moon counted) reckoning, followed in Maharashtra, Gujarat and much of South India, the same night is the last day of Āśvina. The Gregorian date is the same either way.
On this Amāvasyā, the Sun and Moon share the same longitude in the sidereal sign of Tula (Libra), the scales. The Moon is invisible because its lit face is turned away from us, so the night is dark of moon.
In Jyotiṣa, Tula is the sign where the Sun is nīca, debilitated, deepest at 10° Tula. The season has turned as well. After the autumnal equinox, nights are longer than days, and the Sun’s rays strike the earth at a lower angle, so each unit of ground receives less solar energy and the sunlight wanes. Śāradīya Navarātri, traditionally associated with the autumnal equinox and the turning of the seasons, begins the day after the Āśvina Amāvasyā, and Diwali falls on the next new moon, a lunar month later, as the nights deepen. So after the celebration that acclimates us to the change of season, the first following new moon as the darkness deepens is celebrated as Diwali. On the new moon, both luminaries are low at once: the Sun, our great light, understood to be dim, and the Moon, our other great light, hidden.
This is the cosmic backdrop of the festival. When the lights above are faint, we kindle one below. We light the diya as an act of Agni, to brighten the world outside, we also remember that the flame within us is always available to us when we can’t feel the qualities of our inner Sun or Moon. And even when the Sun and Moon, the outer lights are dim, our inner light can still shine.
The central practice is simple: light a flame.
And in doing so, remember the jyoti within.
Spiritual Interpretation by Sampradaya
Different paths tell this night in different ways, according to what they turn toward to.
For many Vaiṣṇava communities, it is the night Rāma returns to Ayodhyā. The city is lit with rows of lamps so that he can find his way home.
For others, the day before is Naraka Chaturdaśī, when Kṛṣṇa, with Satyabhāmā, slays Narakāsura, and the day itself celebrates that victory.
For many householders, it is Lakṣmī Pūjā, when homes are cleaned, cleared of the darkness of clutter inside and out, and lit to welcome prosperity.
For those on the Goddess path, especially in Bengal, Odisha and Assam, it is Kālarātri, the dark night honored as a night of Śakti’s great power.
Each tradition tells a story of darkness and light in the form that opens its hearts toward the divine. The sky gives the moment, and the stories give it meaning. Coming back to the Jyotiṣa lets us see how all these stories rest on the same turning of the cosmos, and gives each of us a way to honor it through the form of the divine we love most.