Mysteries of gas giants known as ’hot Jupiters’ unravelled

artist's impression of 25 hot Jupiters Five long-standing questions about planets outside our solar system known as "hot Jupiters" have been answered in a major new study led by UCL researchers. The study, published in The Astrophysical Journal Supplement Series , is one of the largest ever surveys of exoplanet atmospheres ever undertaken. Researchers employed high performance computers at the DiRAC HPC facility to analyse the atmospheres of 25 hot Jupiters using data from about 1,000 hours of telescope observations. Hot Jupiters are gas giants that orbit close to their star, typically in less than 10 days. While there are none in our own solar system, they are a commonly observed type of planet outside it. By using a large sample of exoplanets and analysing an extremely large amount of data, the researchers were able to determine trends and resolve questions that smaller studies have been unable to conclusively answer over many years. Among the findings, the researchers discovered that the night and day sides of hot Jupiters are very different, with temperatures plunging by hundreds of degrees centigrade from day to night (on average the researchers found a 1000K difference).