Henri B. Kagan and Kenso Soai won the Nobel Prize in chemistry Wednesday for their efforts to resolve mysterious mirror images in chemical molecules.

“Henri Kagan and Kenso Soai have provided a solution to a chemical mystery that is over a century old: how homochirality can emerge spontaneously,” Heiner Linke, chair of the Nobel Committee for Chemistry, said in a news release. “The chemical reactions they have developed are spectacular.”

Kagan, 95 years old and born in France, is affiliated with Université Paris-Sud in Orsay, France, and Soai, born in Japan, with the Tokyo University of Science.

Soai said he was shopping near his home when he was reached by the Nobel committee.

The Royal Swedish Academy of Sciences announced the winner in Stockholm.

Last year, three scientists won the chemistry Nobel for their development of new molecular structures that can trap vast quantities of gas inside, laying the groundwork to potentially suck greenhouse gases out of the atmosphere or harvest moisture from desert environments.

This year’s prizes began with the Nobel for medicine, awarded Monday to three scientists whose work led to a tool that uses light to help unravel how the brain works.

The physics award Tuesday recognized a scientist’s efforts to demystify a rare group of neutrinos.

The literature prize is set to be awarded Thursday.

After Friday’s peace prize is awarded, the Nobel Memorial Prize in Economic Sciences will be announced Monday.

The prize money this year is 12 million Swedish kronor (about $1.2 million), whether for an individual, a small group of laureates or an organization.