Triton's Summer Sky of Methane and Carbon Monoxide

According to the first ever infrared analysis of the atmosphere of Neptune's moon Triton, summer is in full swing in its southern hemisphere. The European observing team used ESO's Very Large Telescope and discovered carbon monoxide and made the first ground-based detection of methane in Triton's thin atmosphere. These observations revealed that the thin atmosphere varies seasonally, thickening when warmed.