Researchers from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., provided new evidence stating mysterious molecules in space are composed of silicon-capped hydrocarbons instead of carbon atoms, as astronomers previously thought.

Astronomers are able to detect molecules in space by measuring the intensity of radiation according to its wavelength. Each light emits different colors, which determine the type of molecule present in space. For instance, gaseous nitrogen dioxide appears to be reddish brown, causing a polluted sky to most often bear this color.

Scientists long-believed the molecules in space were composed of carbon, hydrogen, silicon, and other atoms. These molecules were presumed to be emitted by stars, and formed 20 percent of the all the carbon in the universe. Another hypothesis stated these molecules were responsible for the cosmic mystery of "diffuse interstellar bands," or the absorption features seen in the spectra of space objects in our galaxy, causing humans to see different colors in the sky. Its origin is unknown, and there is continuous debate on its composition - but this new study may shed light on the mystery.

"There have been a number of explanations over the years, and they cover the gamut," said Michael McCarthy, lead author and senior physicist at the Harvard-Smithsonian Center for Astrophysics.

McCarthy and his colleagues created silicon-containing carbon chains SiC3H, SiC4H and SC5H in the laboratory using a jet-cooled silane-acetylene discharge. They then observed that the silicon-carbon chains changed color from black to multiple other shades as they increased the wavelength, indicating that the chains could constitute the molecular source of these interstellar bands. The researchers admitted further research is needed to establish this notion. They planned to continue their study to determine the types of transitions the molecules underwent before changing colors.

"The interstellar medium is a fascinating environment," McCarthy said. "Many of the things that are quite abundant there are really unknown on Earth."

Further details of the study were published in the Journal of Chemical Physics.