The NGC 7027 nebula – home to some ancient-looking molecules William B. Latter (SIRTF Science Center/Caltech) and NASA/ESA

In the beginning, there were no molecules. For hundreds of thousands of years after the big bang, the universe was too hot and full of radiation for atoms to bond together – but now, for the first time, we have spotted the first type of molecule to arrive on the scene.

Just after the big bang, there were only three kinds of atoms: the three lightest elements: hydrogen, helium and lithium. Temperatures throughout the universe were in the thousands of degrees, and harsh …