An international team of astronomers using ESO's Very Large Telescope has discovered that the south pole of Neptune is much hotter than the rest of the planet. This is consistent with the fact that it is late southern summer and this region has been in sunlight for about 40 years.
The scientists are publishing the first temperature maps of the lowest portion of Neptune's atmosphere, showing that this warm south pole is providing an avenue for methane to escape out of the deep atmosphere.
"The temperatures are so high that methane gas, which should be frozen out in the upper part of Neptune's atmosphere (the stratosphere), can leak out through this region," said Glenn Orton, lead author of the paper reporting the results.