A NASA-led team of scientists determined that WASP-18b, a 'hot Jupiter' located 325 light-years from Earth, has a stratosphere that's loaded with carbon monoxide, but has no signs of water.

WASP-18b (Artist’s Concept)

WASP-18b is an exoplanet located 325 light-years from Earth. The planet's mass is 10 times that of Jupiter, and it orbits its star once every 23 hours. A 2017 study found that this planet has a stratosphere that's loaded with carbon dioxide, but has no signs of water. A stratosphere is a layer of atmosphere in which temperature increases with higher altitudes. The study used NASA's Spitzer and Hubble space telescopes. https://photojournal.jpl.nasa.gov/catalog/PIA22087