The researchers found that the planet’s temperature dropped in an unforeseen way – and then warmed dramatically at the South Pole. The researchers made the discovery after observing the temperature changes of the planet for 17 years. “This change was unexpected,” Michael Roman, lead author of the new study, said in a statement. “Given that we observed Poseidon at the beginning of its southern summer, we expected that temperatures would rise slowly and not colder.” The variations were so shocking that researchers are not yet able to explain them. They could be the result of planetary chemistry, weather patterns or changes in the Sun – and researchers hope to answer that question and more with future observations. “I think Poseidon is himself very intriguing to many of us because we still know so little about him,” said Dr. Roman. “All this shows a more complex picture of Poseidon’s atmosphere and how it changes over time.” Poseidon goes through seasons, as does the Earth, as it moves around the Sun. But a period of Poseidon is much longer, about 40 years, since a whole year of Poseidon lasts 165 earth years. This meant that scientists wanted to understand how these long-term seasonal changes could occur, especially in the wake of the summer solstice south of Poseidon. To observe them, scientists examined nearly 100 thermal infrared images of the planet. They found that although summer had arrived, most of the planet was cold. But then the south pole started to heat up again. Between 2003 and 2018, the average temperature across the planet dropped by 8 degrees Celsius. Then, at the South Pole, it increased by 11 degrees Celsius between 2018 and 2020. None of these rapid changes were expected by scientists. The period covered is less than one season, and so scientists expected much more gradual fluctuations. The research is described in a new publication, “Sub-seasonal variation in Poseidon’s mid-infrared emission”, published in The Planetary Science Journal today.
