Detections of trace abundances of methane on Mars, as well as a handful of larger emission spikes, have fueled debates about whether their source could be biological or geological. Science Magazine reports on a new aspect to the story, presented at last month’s Fall Meeting of the American Geophysical Union (AGU) in New Orleans, Louisiana: evidence that the abundance of martian methane follows a seasonal pattern, which rises to a peak in late northern summer. READ MORE »