The Surprising Change Scientists Found In Neptune's Temperature

Neptune, a cold gas giant that is about four times bigger than the Earth and the farthest planet from our Sun in the Solar System, hasn't really been the subject of in-depth research as much as fellow planets like Jupiter, Mars, and Venus. However, new research shows that the dark, windy planet has more surprises hidden in its atmosphere than scientists previously assumed. Studying nearly two decades' worth of data collected from observatories across the world, a team from the University of Leicester noticed that the planet has undergone some unusual temperature changes lately. 

Sifting through observations made in the infrared region, the team noticed that the average global temperature of Neptune's stratosphere had fallen by 8-degrees Celcius between 2003 and 2018. The temperature change trend was expected to be the opposite, as the phase in which data on the planet was collected was supposed to be the summer season. "This change was unexpected. Since we have been observing Neptune during its early southern summer, we would expect temperatures to be slowly growing warmer, not colder," said the lead author of the research, Dr. Michael Roman in a statement with the University of Leicester.

Long seasons, big mysteries

Just like Earth, Neptune is also tilted and experiences seasonal variations similar to summer and winter on Earth. The only difference is that Neptune's orbital period is 165 years, which means the seasons don't last for months as they do on Earth. Instead, Neptunian seasons last over four decades. The summer season in which the data on Neptune's stratosphere was recorded was expected to have shown a rise in temperature, but the scientists have been left stunned with data that suggests the opposite.

Further studies showed that between 2018 and 2020, the planet's southern pole actually got warmer, recording an 11-degrees Celcius rise in temperature. The phenomenon of polar warming hasn't been documented on Neptune, even though a similar process on Earth has left environment scientists in great concern. The rise in polar temperature is surprisingly swift, especially considering the fact that the planet's South Pole has been subjected to constant solar illumination since 1963, according to the research paper published in The Planetary Science Journal

A few more decades of study needed

Scientists suspect that some unexplained processes are happening in Neptune's atmosphere at a sub-seasonal scale, and on both regional and global levels, to trigger these unexpected temperature changes. Though the team hasn't zeroed down on the exact reasons why these temperature variations are taking place, they've suggested that a change in atmospheric chemistry due to the variation in sunlight exposure could be the key. It is worth noting here that the entire dataset covers less than half of a single Neptunian season, and scientists behind the research aren't sure what to expect in the years to come. 

Even though the fundamental reasons behind this mysterious temperature change, just the latest in a line of mysteries about Neptune, are not known, a new season is about to kick off on Neptune, opening the doors for a more comprehensive study of Neptune over the next few decades with regular observations. Further study of Neptune and its place in our Solar System combined with a better understanding of its atmospheric and surface properties could shed more light on how other distant icy exoplanets operate in the cold reaches of space.