Although we already knew that Uranus is probably one of the most hostile places for life in the Solar System, now we have one more reason not to travel to this planet: its smell. And it is that a team of scientists has just demonstrated that in the upper layers of the atmosphere of Uranus hydrogen sulfide abounds , a gas responsible for the classic smell of rotten eggs.
The researchers, publishing their work in the journal Nature Astronomy , have discovered that this harmful gas swirls in the clouds of the giant planet. Although it was something that was suspected, no one until now had been able to demonstrate the composition of these clusters.
Why is it so difficult to study the composition of the clouds of Uranus? According to Leigh Fletcher, from the University of Leicester, when a cloud layer is formed by condensation, the forming gas is trapped in an internal reservoir at such low levels that they are very difficult to detect by most of the instruments used until now. “Only a small amount remains above the clouds in the form of saturated vapor,” explains the scientist.
The finding has been made possible thanks to the Gemini North telescope, located on Mauna Kea (Hawaii), with which the researchers were able to capture the sunlight by reflecting off the upper layer of the Uranus clouds and analyzing it using spectrometry. “Thanks to the improved hydrogen sulfide absorption line data and the wonderful Gemini spectra, we have the fingerprint we needed to ‘catch’ the culprit,” explains Patrick Irwin, a researcher at the University of Oxford and lead author of the study. “The lines we were trying to detect were very faint, but due to the high sensitivity of the Gemini spectrometer and the good weather conditions on Mauna Kea we were able to detect them unequivocally.”
Exploring the history of our Solar System
The work highlights the differences between the so-called “gas giants” (Jupiter and Saturn) and the “ice giants” (Uranus and Neptune). While in the former it is ammonia that is detected in the clouds, in Uranus, and possibly in Neptune as well, hydrogen sulfide is the main component. According to Leigh, these differences would have originated from the very moment the planets were born. “During the formation of the Solar System, the balance between nitrogen and sulfur – and therefore between ammonia and hydrogen sulfide – was determined by the temperature and location of each planet.”
These findings reveal that, although the atmosphere of Uranus is a tremendously unpleasant place for humans, this vast world is fertile ground for exploring the history of our Solar System and perhaps also for understanding conditions on other large icy planets that stars orbit beyond our Sun.
With their discovery, the team of researchers has also found a new application for the large telescope. “This work represents a new and innovative use for an instrument originally designed with the aim of analyzing explosive environments around black holes located at the center of distant galaxies,” explains Chris Davis, from the National Science Foundation (USA). , one of the funders of the Gemini telescope. “Using it to solve a mystery in our Solar System is a new application with a lot of potential for future research.”
Reference: Irwin et al, 2018. Detection of hydrogen sulfide above the clouds in Uranus’s atmosphere. Nature Astronomy volume 2, pages420–427
