Scientists have detected extraterrestrial clouds covering two of the most common types of planets in the Milky Way, according to NASA.

Two teams of researchers used the Hubble Space Telescope to characterize the atmospheres of the two exoplanets.  One of them is called a “super-Earth” since it is larger than Earth, while the other has been dubbed “warm-Neptune” as its orbit is closer to its parent star than the distance between Neptune and the sun in our solar system.

As both planets pass in front of their parent stars, the atmosphere creates a bloated sphere that precedes the body of the planet in the front and follows it in the back.  Scientists have studied how light changes to determine the compositions of the atmospheres it penetrates.

For warm-Neptune, formally called GJ 436b, the study of light was unusual in what the researchers could not find.  The light 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,” Heather Knutson of the California Institute of Technology said.

In a separate study, researchers examined super-Earth, also called GJ 1214b, and obtained similar results – featureless light that led to the conclusion that the atmosphere could be predominantly water vapor or hydrogen.

The Hubble Space Telescope allowed this second team to get a deeper view of the planet’s atmosphere, finding evidence of high clouds covering the planet.  No chemical signs were revealed in the clouds, but researchers were able to rule out water vapor, methane, nitrogen, carbon monoxide, and carbon dioxide in them.  Models of both planets predict the clouds could be made of potassium chloride or zinc sulfide.

The Hubble Space Telescope’s maximum capabilities were utilized in this research.  The launch of the James Webb Space Telescope at the end of the decade will allow for an even more detailed look at distant planets.