Telescopes such as APEX, which make observations of light at millimetre- and submillimetre-wavelengths, are ideal for detecting the signals from these molecules.Now, the team has found the characteristic signature of light emitted by hydrogen peroxide, coming from part of the Rho Ophiuchi clouds."We were really excited to discover the signatures of hydrogen peroxide with APEX," says Per Bergman, astronomer at Onsala Space Observatory in Sweden and lead author of the study.“We knew from laboratory experiments which wavelengths to look for, but the amount of hydrogen peroxide in the cloud is just one molecule for every ten billion hydrogen molecules, so the detection required very careful observations," he added.The study has been published in the journal Astronomy and Astrophysics.