11.5 Festivals & Satellites

The sky-cycles we’ve traced don’t just fill textbooks — they set the dates of our festivals and guide the newest objects we’ve placed in orbit.

Why festival dates move

Festivals Tied to the Moon Many Indian festivals follow the Moon’s phases (lunar or luni-solar calendars), so their Gregorian dates shift each year:

  • Diwali — the new Moon of Kartika;
  • Holi — the full Moon of Phalguna;
  • Buddha Purnima — the full Moon of Vaisakha;
  • Eid-ul-Fitr — after sighting the crescent Moon ending Ramazan;
  • Dussehra — the tenth day of Ashwina.

Luni-solar festivals shift by less than a month (the Adhika Maasa keeps them near the seasons); purely lunar festivals like Eid can fall in different Gregorian months year to year.

A Step Further: Festivals Fixed to the Sun A few festivals — Makar Sankranti, Pongal, Bihu, Vaisakhi, Poila Baisakh, Puthandu — follow a solar (sidereal) calendar, so they land on nearly the same Gregorian date every year. (Over very long times they drift slightly — Makar Sankranti moves about one day every 71 years — because of a slow wobble of the Earth’s axis, like a spinning top.) To keep festival dates uniform across India, the Positional Astronomy Centre publishes the Rashtriya Panchang each year. The Moon and Sun also inspire Indian ragas (Chandrakauns), dance mudras (Chandrakala), and art (Warli, Madhubani).

Artificial satellites

Natural and Man-Made Satellites The Moon is Earth’s natural satellite. But the night sky also holds artificial satellites — human-made objects launched into orbit, appearing as tiny points of light moving fast across the sky. Most orbit about 800 km up and circle the Earth in roughly 100 minutes. They power communication, navigation, weather monitoring, disaster management and scientific research.

India in Space: ISRO The Indian Space Research Organisation (ISRO) has launched many satellites: the Cartosat series (mapping, via the Bhuvan platform), AstroSat (studying stars), the Chandrayaan 1, 2 & 3 Moon missions, Aditya-L1 (the Sun), and Mangalyaan (Mars). ISRO even lets students build and launch small satellites like AzaadiSat and Jugnu.

A Step Further: Space Debris When satellites and rocket parts finish their useful life, many become space junk (debris) crowding orbit — and risk colliding with working satellites. Small pieces burn up in the atmosphere, but larger ones can reach the ground. Countries are now cooperating to clean up this dangerous debris.

Be a Scientist: Vikram Sarabhai Vikram Sarabhai (1919–1971), a researcher in space science and nuclear physics, is called the Father of the Indian Space Programme. He pioneered India’s first artificial satellites; the Vikram Sarabhai Space Centre in Thiruvananthapuram, which develops ISRO’s rockets, is named after him.