Super-Earth GJ 1214b orbits a star situated 40 light-years from Earth .
It is shrouded by clouds and its star raises it temperature to around 232°C.
GJ 436b atmosphere, 36 light years away, has no chemical fingerprints.
This could be because the planet has a high cloud layer obscuring the view.
The work is an important milestone to characterising potentially habitable, Earth-like worlds beyond the solar system.
Evidence of extraterrestrial clouds covering two of the most common types of planets in our galaxy have been discovered by the Hubble telescope.
The atmospheres were discovered by two separate teams of scientists who were analysing the climate of planets GJ 436b and GJ 1214b.
The researchers claim their work is an important milestone in characterising potentially habitable, Earth-like worlds beyond the solar system.
Its parent star also raises temperatures to 232°C and these weather conditions are expected to last ‘for the foreseeable future’.
GJ 436b is categorised as a ‘warm Neptune’ because it is much closer to its star than frigid Neptune is to our sun.
The planet is located 36 light-years away in the constellation Leo.
GJ 1214b, meanwhile, is known as a ‘super-Earth’ type planet. Super-Earths have masses between that of Earth and Neptune.
Because no such planet exists in our solar system, the physical nature of super-Earths is largely unknown. GJ1214b is located just 40 light-years from Earth, in the constellation Ophiuchus.
‘Both planets are telling us something about the diversity of planet types that occur outside of our own solar system; in this case we are discovering we may not know them as well as we thought,’ said Heather Knutson of the California Institute of Technology.
The planets can be observed passing in front of, or transiting, their parent stars. This provides an opportunity to study these planets in more detail as starlight filters through their atmospheres.
For the Neptune-like GJ 436b, the results were more about what the researchers didn’t find. The light, or spectra, was featureless, revealing no chemical fingerprints in the planet’s atmosphere.
‘Either this planet has a high cloud layer obscuring the view, or it has a cloud-free atmosphere that is deficient in hydrogen, which would make it very unlike Neptune,’ said Professor Knutson.