Decoding the stars

We’ve all stared at the night sky, wondering what makes the stars shine so brightly. For some, it’s just a passing thought before sleep. For others, it’s a lifelong mystery: twinkling above but never answered. But one man, born in a small village in colonial India, dared to ask not only why the stars shine but also how we can read their light.

That man was Meghnad Saha. With a restless curiosity and a brilliant mind, he found a way to decode the stars themselves — revealing that the glowing giants above us follow rules written in the language of physics. His discovery, the Saha ionisation equation reshaped astrophysics and gave humanity a tool to peer deeper into the cosmos.

Born on October 6, 1893, in Seoratali, near Dhaka (then in British India), Saha’s journey from humble beginnings to scientific greatness was driven by a passion for discovery and perseverance. In 1920, he formulated the thermal ionisation equation, a groundbreaking concept that explained how the temperature of a star determines the way its

atoms release light. The equation became a cornerstone for interpreting stellar spectra — the colorful fingerprints of stars — allowing scientists to uncover what stars are made of and how hot they truly are.

British astrophysicist Edward A Milne later refined Saha’s equation, but its foundation remained his own — a testament to his visionary understanding of cosmic physics. By 1923, Saha was a professor of physics at the University of Allahabad, where his lectures inspired a generation of Indian scientists to dream beyond Earth’s horizon. Four years later, in 1927, his contributions earned him the rare honour of being elected a Fellow of the Royal Society in London.

When he joined the University of Calcutta in 1938, Saha’s ambitions expanded from pure research to institution-building. He played a key role in founding the Institute of Nuclear Physics, an institution that would later evolve into one of India’s leading centers for scientific research.

Saha’s vision wasn’t confined to laboratories or equations. He believed science must serve society. In 1935, he launched the journal Science and Culture, creating a platform where ideas about science, progress and public welfare could meet. By 1951, his belief in reason and reform took him to the Parliament, where he served as an

independent voice for scientific thinking in national policy.

Throughout his life, Saha also authored influential works, including A Treatise on Heat and A Treatise on Modern Physics, and penned landmark papers like Ionisation in the Solar Chromosphere. His ideas transformed our understanding of stars — and reminded humanity that even the farthest lights in the sky can be brought closer through the power of thought.

Meghnad Saha passed away on February 16, 1956, due to a cardiac arrest, leaving behind not just equations, but a legacy that continues to illuminate how we see the universe.