An international team of astronomers has summarised 17 years of global temperature observations on Neptune. Researchers have documented an anomaly: a sudden drop in Neptune's temperature followed by a sharp warming at its south pole.
The study is published in The Planetary Science Journal and is summarised on the European Southern Observatory (ESO) website. For 17 years, a team of astronomers has been observing Neptune using various ground-based telescopes, including the Very Large Telescope VLT. As a result, the scientists recorded periods of global temperature decrease and increase that did not fit within theoretical predictions.
"This change was unexpected," says lead study author Michael Roman of the University of Leicester. - "As we were observing Neptune at the start of the southern summer, we expected temperatures to rise slowly, not fall.
In reality, however, the opposite happened. Despite the onset of the southern summer, most of Neptune has been gradually cooling over the past two decades. The average global temperature on this planet fell by 8 degrees Celsius between 2003 and 2018.
Then, between 2018 and 2020, the temperature began to rise rapidly and rose by 11 degrees Celsius during that time. Scientists note that there is a so-called warm polar vortex on Neptune that has been known about for years. However, a polar vortex bringing warming so fast has never been observed before.
In all, astronomers have studied almost 100 thermal infrared images of Neptune in 17 years of observations. This allowed them to collect and summarise data on temperature changes on the planet's surface for the first time. This is the first detailed study of its kind.
Like Earth, Neptune experiences the changing seasons as it too revolves around the Sun. But because Neptune is much farther from the star than our planet, one season on Neptune lasts about 40 years, while one year on Neptune equals about 165 Earth years. By the way, summer in the southern hemisphere of this planet began in 2005. The average temperature there reaches minus 220 degrees Celsius.
