Are Festivals Related to Astronomical Phenomena? (11.3) — "Keeping Time with the Skies"

1. 13 marks

   Name the Moon-phase or lunar-month basis for Diwali, Holi, Buddha Purnima, Eid-ul-Fitr and Dussehra.

   Hint. Each festival is tied to a specific phase and, for most, a specific lunar month.

   ✦ Diwali falls on the new Moon of Kartika; Holi on the full Moon of Phalguna; Buddha Purnima on the full Moon of Vaisakha; Eid-ul-Fitr is celebrated after sighting the crescent Moon at the end of Ramazan; and Dussehra falls on the tenth day of the month of Ashwina — since each is fixed to the Moon rather than a Gregorian date, all of them shift from year to year.

2. 23 marks

   Why does Eid-ul-Fitr shift across Gregorian calendar months more dramatically, year to year, than Diwali does?

   Hint. One festival's calendar corrects the lunar shortfall against the solar year; the other's does not.

   ✦ Diwali is fixed by a luni-solar calendar, which periodically inserts an intercalary month (Adhika Maasa) to correct the roughly 11-day-per-year shortfall between the lunar and solar year — so its Gregorian date shifts, but typically by less than a month. Eid-ul-Fitr follows a purely lunar calendar, which makes no such correction, so the 11-day shortfall accumulates freely year after year, letting the festival drift steadily through every month of the Gregorian calendar over time.

3. 33 marks

   A step further: which Indian festivals follow a solar sidereal calendar, and why do they land on nearly the same Gregorian date every year?

   Hint. These festivals were originally tied to a solstice or equinox rather than to a Moon phase.

   ✦ Makar Sankranti, Pongal, Bihu, Vaisakhi, Poila Baisakh and Puthandu follow a solar sidereal calendar. Because the Gregorian calendar is itself based on the tropical year (not the sidereal year), and both are solar-based (not lunar), these festivals land on almost the same Gregorian date every single year — unlike Moon-based festivals, which shift because they are tracking an entirely different, shorter lunar cycle.

4. 43 marks

   Why does the date of Makar Sankranti slowly drift over long periods of time, moving ahead by about one day every 71 years?

   Hint. This isn't a lunar-calendar shortfall — it's a slow, separate astronomical effect on Earth's own axis.

   ✦ These festivals were originally tied to a solstice or equinox, but the sidereal and tropical years differ very slightly (by only 20 minutes), and this tiny difference accumulates over centuries due to the slow wobble of Earth's axis (similar to a wobbling spinning top). This gradual wobble causes festival dates fixed to the sidereal calendar to slowly move away from the solstice/equinox they were originally anchored to, and ahead in the tropical (Gregorian-based) calendar — which is why, for Makar Sankranti, this amounts to about one day every 71 years.

5. 52 marks

   Ever heard of... why does the Government of India publish the Rashtriya Panchang, and what specific problem does it solve?

   Hint. Sunrise itself doesn't happen at the same clock time everywhere in India.

   ✦ Because many Indian festival dates are fixed by the exact lunar phase at sunrise, and sunrise occurs earlier in Eastern India and later in Western India, the same festival could otherwise fall on different dates in different regions in the same year. The Positional Astronomy Centre publishes the Rashtriya Panchang annually — a detailed calculation of Sun and Moon positions for a central Indian location — to give the Government of India a single, uniform basis for declaring festival-based holidays nationwide.

6. 62 marks

   Give two examples of the Moon's presence in Indian classical arts, as described in the chapter.

   Hint. The chapter names specific ragas, dance mudras, and painting/craft traditions.

   ✦ Any two of: ragas named after the Moon (Chandrakauns, Chandranandan, Shubhapantuvarali — 'auspicious moon'); Bharatanatyam mudras relating to the Moon (Chandrakala, Ardhachandran), also seen in Kathak, Odissi and Kuchipudi; or traditional painting and craft styles (Madhubani, Warli, Dhokra brass sculpture) since all of them prominently depict the Moon and Sun in daily cultural life.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 11 (hecu111.pdf), Reprint 2026-27, pages 170-189. Questions are referenced from the NCERT textbook for identification.