In a scholarly article published in October 2009, NASA scientists reported having reproduced uracil from pyrimidine by exposing it to ultraviolet light under space-like conditions. This suggests that one possible natural original source for uracil in the RNA world could have been panspermia. More recently, in March 2015, NASA scientists reported that, for the first time, additional complex DNA and RNA organic compounds of life, including uracil, cytosine and thymine, have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the Universe, may have been formed in red giants or in interstellar dust and gas clouds, according to the scientists.