The planets, one reminiscent of Neptune and the other a super-Earth, were examined as part of two separate studies using the Hubble Space Telescope to learn more about their atmospheres.
For the Neptune-like world which was located 36 light years away, researchers found that they were unable to pick up any chemical fingerprints in the planet's atmosphere at all. "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 researcher Heather Knutson.
In the second study, researchers investigating a super-Earth world located 40 light years away found even clearer signs of cloud cover in its atmosphere. Using high-precision instruments they were able to rule out the presence of water vapor, methane, nitrogen, carbon monoxide, or carbon dioxide.
"We really pushed the limits of what is possible with Hubble to make this measurement - our work devoted more Hubble time to a single exoplanet than ever before," said team leader Laura Kreidberg. "This advance lays the foundation for characterizing other Earths with similar techniques."