100 years ago, Cecilia Payne discovered what the stars are made of

100 years ago, Cecilia Payne discovered what the stars are made of

Inside the Sun, the most powerful source of energy for several light-years in all directions, an incredible process occurs. Deep within its core, hundreds of thousands of kilometers beneath the edge of its photosphere, temperatures exceed a critical threshold of four million degrees, rising up to a maximum of 15 million K in its center. Under these conditions, hydrogen atoms — and specifically, the nuclei of hydrogen atoms — smash into one anoth…