When moon is shaped like a crescent, it is in the stage (or phase) of New Moon. A phase of new moon arrives at when the Sun and moon are aligned face to face and Earth stands on the opposite side of the moon. In this celestial position, Earth sees the dark side of the moon while the Sun is shining on the opposite side. It happens every 29.5 days.

The trio’s alignment leaves the side of the moon facing the Earth in total darkness popularly called Amavasya in eastern civilization.The word Amavasya is common to almost all Nepalese and Indian languages as most of them are derived from Sanskrit. The New Moon tithi(called Pratipada or Prathama). In Sanskrit, “amā” means “together” and “vásya” means “to dwell” or “cohabit”. It also means “na” +”ma”+”asya” meaning to “na”- “No, “ma”-moon, “Asya”-“there”. Put together, it means, ‘there is no Moon'(or ‘Moon is not visible’).

In Sanatan Dharma (popularly known as Hindu Dharma or Hinduism all over the world), Diwali or Lakshami Puja is performed on Amawasya (the New Moon phase in month of Ashvin or Asoj of Hindu calendar). Hindus worship Lakshami – the goddess of wealth and Ganesh – the God of auspicious beginnings also known as obstacle remover) and light Deeyas (small clay pots) in the streets and homes to welcome prosperity and wellbeing on Deewali.

In astronomy, the new moon is the first lunar phase and at this phase moon (or a lunar disc) is not visible to human eyes (the unaided eyes). The new moon also rises and sets at around the same time as the Sun while the full moon rises at sunset, transits at midnight and sets at sunrise. During this phase the moon is between Earth and the sun, which means none of the lunar half we see is illuminated, and the moon becomes nearly invisible in the night sky. The waning phase of the moon is the period between full moon day and new moon day while the waxing phase of the moon is the period between new moon day and full moon day.

Philosophical and scientific importance of new moon day go like this: the earth broods on new moon (Amavasya); the life process is slowed down on the planet and it is a great opportunity because the integration of life happens much better on this day — all in darkness with no agitation of sparks of light.