James Webb telescope reveals rare, 'rotten egg' atmosphere around nearby hell planet

A hellish "hot Jupiter" planet situated relatively close to Earth would likely smell like rotten eggs if we ever made the trip to visit it, new data from the James Webb Space Telescope (JWST) reveals. 

HD 189733 b is a gas giant located around 64 light-years away in the Vulpecula constellation. It orbits extremely close to its home star — around 13 times closer than Mercury orbits the sun — and completes one orbit every two days. As a result, the exoplanet's surface can reach a scorching-hot 1,700 degrees Fahrenheit (925 degrees Celsius) — hot enough to melt certain types of rocks into magma.

Previous observations revealed that the exoplanet likely rains molten glass, which is probably blown sideways by winds that travel up to 500 mph (800 km/h) — around three times faster than a Category 5 hurricane on Earth. 

In a new study, published July 8 in the journal Nature, researchers turned JWST toward HD 189733 b to learn more about the unique alien world. In addition to measuring the amount of carbon dioxide, oxygen, water and heavy metals in the exoplanet's atmosphere, the team discovered that it contained hydrogen sulfide — a toxic and flammable colorless gas given off by decaying organic matter and volcanoes on Earth, which smells like rotten eggs.

The researchers had previously suspected that hydrogen sulfide could be found on distant gas giants because the atmospheres of Jupiter and Uranus contain the same molecule. However, the gas has rarely been spotted outside of the solar system apart from trace amounts in the interstellar medium, or space between stars, researchers wrote in a statement. 

The discovery of hydrogen sulfide on HD 189733 b is an important "stepping stone for finding this molecule on other planets and gaining more understanding of how different types of planets form," study lead author Guangwei Fu, an astrophysicist at Johns Hopkins University in Maryland, said in the statement.

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