Frigid and far-flung Neptune, our solar system's outermost planet, is adding to its reputation as an enigmatic world, with astronomers puzzled by a surprising drop in its atmospheric temperatures during the past two decades.
Focusing upon Neptune's stratosphere - the atmosphere's relatively stable region above the turbulent weather layer - the researchers had expected to find rising temperatures in the part of the planet visible from Earth with the onset of its southern hemisphere summer, a season lasting four decades. Instead, they found temperatures declining significantly.
