
Neptune’s temperature has been showing some abnormalities recently. For example, in 2019, NASA released images of Neptune going through massive storms during the summer period of planet’s southern hemisphere. And now an international team of astronomers has discovered unexpected changes in Neptune’s temperature.
Michael Roman at University of Leicester and his colleagues have used ground-based telescopes, as well as the european Southern Observatory’ very large Telescope (ESO’ VLT) to trace the temperature changes of Neptune since the first comparatively detailed measurements that were made in 2003.
Finally, observations have shown that the temperature in the planet’s southern hemisphere has dropped surprisingly, despite measurements being taken during the planet’s summer, according to a study published today in the Planetary Science Journal.
To measure the planet’s temperature, astronomers used thermal imaging cameras, which measure the infrared light emitted by astronomical objects. And then they collected all of the images of Neptune over the past two decades and studied the infrared light emitted by a layer of Neptune’s atmosphere called the stratosphere. This resulted in an image showing temperature and its variations during part of Neptune’s southern summer.

Souce: M. Roman/ESO
“This change was unexpected,” says Michael Roman, a post-doctoral researcher at the University of Leicester and lead author of the study. “Since we observed Neptune in early southern summer, we expected temperatures to slowly warm up, not coolder.
Dramatic temperature changes
Like other planets in the solar system, Neptune experiences seasons as it orbits the Sun, but these seasons differ from Earth’s in that they last about 40 Earth years.
The southern hemisphere of planet has been experiencing summer since 2005. In addition to the fact that the southern hemisphere cooled by 46°F between 2003 & 2018, the temperature is also reported to have risen rapidly by 51°F between 2018 & 2020
“Our data covers less than half of a Neptune season, so no one expecting to see large & rapid changes,” says Glenn Orton, senior research scientist at Caltech’s Jet Propulsion Laboratory & co-author of the study.
The study sheds light on how dramatically the planet’s temperature can change. The reason for these rapid fluctuations is also intriguing as very little is known about the eighth planet. Therefore, more observations will be needed in the coming years to explain what is happening on with the temperature of planet.