Astronomers have uncovered the secrets of an alien atmosphere on an exoplanet far beyond our solar system, and it’s unlike anything we’ve ever seen before.
For the first time in science, an international team of astronomers has created a 3D map of the atmosphere of the planet WASP-121b, also known as Thylos. Using the European Southern Observatory’s Very Large Telescope (yes, that’s really what it’s called), they found complex weather patterns and a surprising chemical composition. Their study, published Tuesday in an early, unedited version in the journal Nature, paves the way for future research into extraterrestrial atmospheres.
“This planet’s atmosphere is behaving in a way that challenges our understanding of how weather works – not just on Earth, but on all planets. It’s like something out of science fiction,” said Julia Victoria Seidel, a physicist at the European Southern Observatory (ESO) in Chile and lead author of the study, in an ESO statement. It is worth noting that since the official definition of a “planet” remains limited to celestial bodies within our solar system (some astronomers have suggested this should be changed), Thylos is technically an exoplanet – but astronomers sometimes stick with the term “planet” for simplicity’s sake.
The exoplanet in question is a gas giant (a large planet composed primarily of helium and/or hydrogen) located about 900 light-years from Earth. It orbits its star in just 30 hours – so close that Tylos is also classified as an ultra-hot Jupiter: an extremely large and hot planet with a very tight orbit. The time it takes for Tylos to complete one orbit is equal to the time it takes the gas giant to complete one revolution, which means that one side of Tylos is constantly facing its star and is much hotter than the other (i.e., it is tidally tidal).
Seidel and her colleagues analyzed the exoplanet’s atmosphere using all four of ESO’s VLT telescope’s arrays. By tracking iron, sodium, and hydrogen, they were able to examine the planet’s separate deep, middle, and upper atmosphere layers.
“The VLT allowed us to study three different layers of the exoplanet’s atmosphere in one fell swoop,” said Leonardo A. dos Santos, an assistant astronomer at the Space Telescope Science Institute in Baltimore who participated in the study. “Such observations are very difficult to make with space telescopes, which underscores the importance of ground-based observations of exoplanets,” he added.
The team then created a 3D map of their observations, revealing the alien atmosphere outside our solar system in unprecedented detail.
“What we found was surprising: the jet stream is rotating matter around the planet’s equator, while a separate stream in the lower levels of the atmosphere is moving gas from the hot side to the colder side. This type of climate has never been observed on any planet before,” Seidel explained. Compared to the size and speed of the Taylors jet stream, “even the strongest hurricanes in the solar system seem calm,” she added.
In addition, a companion study published earlier this week in the journal Astronomy & Astrophysics by the same researchers notes the discovery of titanium beneath the jet stream. Previous studies have overlooked this chemical presence, possibly because it is at a great depth in the atmosphere.
“The fact that we can study details such as the chemical composition and weather conditions of a planet at such a vast distance is truly impressive,” says Bibiana Prinot, a PhD student in astronomy and astrophysics at Lund University. “This experience makes me feel that we are on the verge of discovering incredible things that we can only dream about now.” Prinot co-authored the Nature article and led a companion paper.
Prinot’s enthusiasm is well founded. Future telescopes, such as ESO’s upcoming Extremely Large Telescope (ELT), will allow researchers to conduct similar atmospheric analyses of smaller Earth-like planets. “ELT will be a game changer in the study of exoplanet atmospheres,” Prinot concluded.
