When atoms collide

via hte.si.edu

On Earth, we can use our five senses to learn about the world around us, but the primary way that we learn about more remote phenomena is through our perception of light in its various forms, and most light is produced by collisions of atoms with each other or with electrons.

The wavelength of the light produced by collisions depends on the speed of the colliding atoms, and the structure of the atom, which varies from one element to the next. Room-temperature collisions typically produce infrared light, higher speed collisions produce optical and ultraviolet light, and collisions typical of multimillion degree gases produce X-rays.

A supernova remnant contains huge quantities of elements such as oxygen, neon, silicon, sulfur, calcium and iron that were made inside the star and expelled into space. It has been estimated that the Cas A supernova remnant contains enough calcium to make several nonillion (a million trillion trillion) glasses of milk.