Temperatures on the planet – known as VHS 1256 b – are around 830 degrees Celsius, and the atmosphere is dominated by a swirling storm of dust-like particles, researchers say.
Their analysis of the distant world – which is 40 light-years away – also detected methane, carbon monoxide and water on its surface, as well as evidence of carbon dioxide.
This is the largest number of molecules ever identified at once on a planet outside our solar system, the team says.
Space telescope
The discoveries were made using the James Webb Space Telescope. The £10bn instrument is the most powerful space telescope ever constructed.
Professor Beth Biller from the School of Physics and Astronomy was part of the research team, which also involved scientists from the Universities of Arizona, Exeter and UC Santa Cruz.
Giant planet
The planet – first detected in 2015 – is around 12 to 18 times the size of Jupiter, and it orbits not one, but two suns over a 10,000-year period.
During its 22-hour day, the planet’s clouds of large and small grains of silicate – a compound of silicon and oxygen – are constantly mixing and moving, causing temperatures to rise and fall.
The findings suggest VHS 1256 b is only around 150 million years old, which is why its atmosphere is so turbulent, the team says.
Professor Biller says the finer silicate grains in the planet’s atmosphere may be like the tiny particles in smoke, while the larger ones might be more like very hot, very small sand particles.