What To Know
- HD 189733 b is classified as a “hot Jupiter” because of its similarity to our planet’s gas giant.
- To identify hydrogen sulfide in the atmosphere of HD 189733 b, the researchers used the James Webb Space Telescope (JWST), a state-of-the-art instrument designed to probe extraterrestrial atmospheres with unprecedented precision.
- While HD 189733 b is naturally too hostile to support any form of life as we know it, it represents a natural laboratory for studying the mechanisms of planet formation.
Astronomers have recently captured an unusual olfactory signal from a distant exoplanet, HD 189733 b, that is tantalizing even the most robust senses. The planet, already famous for its extreme conditions, has revealed an atmosphere laced with hydrogen sulfide that produces a rotten-egg smell. Located 65 light-years from Earth in the constellation Ursa Minor, the world offers a fascinating glimpse into planetary diversity beyond our solar system.
A planet that smells bad
HD 189733 b is classified as a “hot Jupiter” because of its similarity to our planet’s gas giant. solar system. It has atmospheric characteristics that are as extreme as they are varied. With an incredibly close orbit to its star, just 4.8 million kilometers away, this planet has temperatures reaching 927 degrees Celsius. Hydrogen sulfide, known for its characteristic rotten-egg sulfur smell, has never been conclusively detected outside our solar system. This discovery is therefore not only a first in exoplanet exploration, but it also offers crucial insights into the chemical composition and atmospheric dynamics of extrasolar worlds. To identify hydrogen sulfide in the atmosphere of HD 189733 b, the researchers used the James Webb Space Telescope (JWST), a state-of-the-art instrument designed to probe extraterrestrial atmospheres with unprecedented precision. The observatory is equipped with spectrographs capable of detecting molecular signatures in the infrared spectrum of exoplanets. In the when light from the star HD 189733 passed through the planet’s atmosphere, molecules present absorbed specific wavelengths of that light. The telescope’s spectrographs eventually decomposed that light into a spectrum that revealed the characteristic absorptions caused by the different atmospheric molecules.
Artist’s impression of the extrasolar planet HD 189733b, seen here with its parent star looming behind it. Credits: ESA/NASA/Frédéric Pont, Observatoire universitaire de Ge
Glass storms
Beyond its smelly atmosphere, HD 189733 b also orbits its star in just 2.2 Earth days, making each rotation a chaotic ballet of extreme heat and frigid cold. This close proximity would have created unique conditions, such as glass showers caused by violent winds that carry silicate vapor across the planet’s surface. While HD 189733 b is naturally too hostile to support any form of life as we know it, it represents a natural laboratory for studying the mechanisms of planet formation. Scientists are now investigating whether other hot Jupiters in the universe share this atmospheric characteristic and how it might influence their development and evolution. Future studies will aim to more precisely map variations in atmospheric composition among exoplanets, providing crucial clues to cosmic processes at work beyond our own solar system.
