As noted by Nature News, these clouds would be unlike anything we experience on Earth. Due to the hot, dense nature of GJ 1214b's atmosphere, the clouds are likely rich with zinc sulphide or potassium chloride. These chemicals would be able to condense and form microscopic droplets, thus forming the cloud cover.
"It's the first time that we've been able to characterize the atmosphere of an exoplanet smaller than Neptune," said Kreidberg.
ANALYSIS: Exoplanet Forecast: Cloudy, With Chance of Maelstrom
A similar technique, using Hubble data, was carried out in the GJ 436b study. Once again, spectroscopic data reveal no chemical signature of an atmosphere, an outcome that is completely unexpected from observations of a Neptune-class planet. The most likely explanation is that a thick layer of high-altitude cloud is blanketing the exoplanet, blocking the starlight from passing through the atmosphere, preventing a spectroscopic measurement from being made.
"We always knew the clouds must be there for some planets, but now we have a wave of results telling us that clouds are actually very common," said planetary astronomer Heather Knutson, of the California Institute of Technology (Caltech) in Pasadena, Calif., and lead author of the GJ 436b study.