He washed a doctor's plates for a bed so he could stay in school — and then worked out how to take the temperature of a star.
For half a century astronomers had been sorting starlight into an alphabet. Photograph a star's spectrum, note which dark lines are strong and which have vanished, file the plate under O, B, A, F, G, K or M. Nobody could say what the alphabet spelled. In the spring of 1920 a twenty-six-year-old physicist in Calcutta — a village grocer's fifth child, once thrown out of school for joining a boycott — posted the answer to London. Borrowing the mathematics chemists used for gases splitting apart in heat, Meghnad Saha wrote down how far the atoms in a star's atmosphere would be stripped of their electrons at a given temperature and pressure, and therefore which lines would show and which would not. The alphabet was a thermometer.
Nearly every stellar temperature measured since rests on that equation. Saha was nominated for the Nobel Prize in Physics six times and never received it. He spent the rest of his life on less celestial things — building laboratories, founding a journal, drafting the plan that would tame a killing river, winning a seat in India's first Parliament, and giving the new republic a single calendar.
Sheoratali to the stars
The lifeline
1893
Born at Sheoratali, a village in the Dacca district of Bengal — fifth of a grocer's eight children
1905
Expelled from Dhaka Collegiate School for joining the boycott of the Governor's visit
1920
At 26 he derives the ionisation equation; the Philosophical Magazine prints it
1927
Elected a Fellow of the Royal Society at the age of thirty-three
1952
Wins a Lok Sabha seat, and chairs the committee sent to reform India's calendars
1956
Dies at 62, on his way to the Planning Commission in Delhi
By the numbers
The measure of him
26
His age when he found how to read a star's temperature from the lines in its light
6
Nominations for the Nobel Prize in Physics, 1930–1955. He was never awarded it.
30
Calendars in use across India that his committee studied before proposing one
99 km
Across — the crater on the Moon's far side that carries his name
What he made
The work
1920
The Saha ionisation equation. Four papers sent from Calcutta to the Philosophical Magazine showed that the spectral sequence of stars is a sequence of temperature. A catalogue became a measurement, and stellar astrophysics became quantitative.
1923–1938
Allahabad. Fifteen years as professor there, building a physics department — and a school of students around it — largely out of nothing.
1935
Science and Culture. Founds the journal and edits it until the day he dies, using it to argue, issue after issue, for an India planned on scientific and industrial lines.
1943
The Institute of Nuclear Physics, Calcutta. Founded in the middle of the war and the Bengal famine. It carries his name today.
1943–1948
The Damodar plan. After the great flood of 1943 he sits on Bengal's Damodar Flood Enquiry Committee and presses for a Tennessee Valley Authority for India. The Damodar Valley Corporation — the country's first multipurpose river project — follows in 1948.
1952–1957
One calendar. Chairs the Calendar Reform Committee, which reports in 1955. India's national calendar, reckoned in the Saka era, takes effect on 22 March 1957 — thirteen months after his death, and still in force.
Passed over, then permanent
Recognition
In his lifetime
Thrown out of school as a boy of eleven for joining a nationalist boycott
Fed by a doctor in exchange for washing the plates and minding the cow
At the Calcutta hostel, fellow students objected to a low-caste boy eating in their dining hall
Six Nobel nominations across twenty-five years; the prize never came
Accused of deserting his laboratory when he turned to rivers and to Parliament
Today
The Saha equation is taught in every astrophysics course on Earth
A 99-kilometre crater on the Moon's far side is named Saha — and has been proposed as a radio-telescope site, shielded from the noise of Earth
The Saha Institute of Nuclear Physics, Kolkata, still bears his name
India's civil calendar still runs on his committee's reform
The Damodar Valley Corporation still works the river he mapped
Where it began
Sheoratali
His village, in the Dacca district of Bengal — Gazipur, in Bangladesh, today — had no schooling past the primary grades. The nearest middle school stood at Simulia, ten kilometres off, and his father wanted the boy behind the counter of the family shop. An elder brother working in a jute company found a sponsor instead: Ananta Kumar Das, a local doctor, who offered free board on the condition that Meghnad wash the plates, run the errands and look after the cow. He took the terms. Twenty years later the Royal Society elected him a Fellow.
10 km
From his village to the nearest middle school, at Simulia
5th
Of the eight children of Jagannath Saha, village grocer
1905
The year a boycott of the Governor's visit cost him his school
"I have gradually glided into politics because I wanted to be of some use to the country in my own humble way."
— Meghnad Saha
