Astronomers have analyzed one of the most extreme known exoplanets, WASP-189 b, and found it has a layered atmosphere just like Earth. But the similarities end there. WASP-189 b is a world twice the mass of Jupiter with temperatures in the thousands of degrees, so we're not upping sticks and moving there.

The reason why it’s so hot is its proximity to its star. It orbits the star in just 2.7 days, being 20 times closer to it than the Earth is to the Sun. But thanks to this alignment, researchers can study its atmosphere in detail. As reported in Nature Astronomy, the international team has established the presence of iron, chromium, vanadium, magnesium, and manganese, as well as titanium oxide in its atmosphere.  

“We measured the light coming from the planet’s host star and passing through the planet’s atmosphere. The gases in its atmosphere absorb some of the starlight, similar to Ozone absorbing some of the sunlight in Earth’s atmosphere, and thereby leave their characteristic ‘fingerprint’," lead author Bibiana Prinoth from Lund University said in a statement. "With the help of HARPS [ESO's planet-hunter], we were able to identify the corresponding substances.” 

The titanium oxide is a particularly exciting find as it has already been linked to an ozone-like layer and stratosphere-like layers on other exoplanets. But these observations went further, finding evidence of additional layers.

“In our analysis, we saw that the ‘fingerprints’ of the different gases were slightly altered compared to our expectation. We believe that strong winds and other processes could generate these alterations. And because the fingerprints of different gases were altered in different ways, we think that this indicates that they exist in different layers – similarly to how the fingerprints of water vapour and ozone on Earth would appear differently altered from a distance, because they mostly occur in different atmospheric layers,” Prinoth explained.

There is a lot that we don’t know about the atmosphere of exoplanets, and to be fair even the atmospheres of the gas giants of the Solar System are still mysterious. This new study sheds some light on how these distant worlds likely do not have a single-layer atmosphere and it's important to appreciate their three-dimensional complexity.

“We are convinced that to be able to fully understand these and other types of planets – including ones more similar to Earth, we need to appreciate the three-dimensional nature of their atmospheres. This requires innovations in data analysis techniques, computer modelling and fundamental atmospheric theory”, study co-author Kevin Heng concluded.