This drop in temperature can be due to many reasons. These include the chemistry of the planet, weather patterns and changes in the Sun. For the last 17 years, many telescopes are being used to observe Neptune. Astronomers using these telescopes have observed a startling drop in the temperature of the planet.
This study was published in The Planetary Science Journal under the name Sub-Seasonal Variation in Neptune’s Mid-Infrared Emission published Has been done Studies show that Neptune has seasons like Earth, but they last much longer. By the time one year ends in Neptune, 165 years pass on Earth and a season there can last for about 40 years.
During the study, scientists wanted to understand the seasonal patterns of the planet Neptune. For this, they looked at nearly 100 thermal-infrared images of Neptune to track temperature changes on its southern side during the summer solstice. Scientists thought summer had arrived, but thermal images showed that between 2003 and 2018, temperatures had dropped by 8 degrees Celsius and much of the planet had cooled. However, soon the South Pole suddenly became hot.
Between 2018 and 2020, the temperature in the South Pole saw an increase of 11 degree Celsius. Scientists studying the planet did not expect this change. They have published their study in The Planetary Science Journal.