"We haven't really figured out the chemistry part of the puzzle yet," said Vos. "But these results are really exciting because they are showing us that the abundances of molecules like methane and carbon dioxide could change from place to place and over time. If we are looking at an exoplanet and can get only one measurement, we need to consider that it might not be representative of the entire planet."

Especially important because exoplanet transit spectroscopy can only look at a planet at one specific phase (time of year, seasonally), when the star and planet line up from the POV of Earth.