Hubble telescope spots clouds on alien planets

By Casey Frye, CCNN Writer

Earth-like planets
From left to right, the planets are as follows: Earth, GJ 1214b, Neptune, and GJ 436b.

Scientists using NASA’s Hubble Space Telescope have made a remarkable discovery about exoplanets – planets outside of our Solar System. They’ve found evidence of extraterrestrial clouds covering the Milky Way’s two most common types of exoplanets: “warm Neptunes” that are much closer to their star than our frosty Neptune, and “super-Earths” that are much larger than Earth. This information can be used to better classify the atmosphere of other Earth-like planets in the future.

In one study, a team of researchers from the California Institute of Technology used Hubble to examine the atmosphere of planet GJ 436b, which is categorized as a warm-Neptune and can complete a full orbit of its parent star in 2.64 days. As it passes in front of its star, the atmosphere creates an expanded sphere around the planet. Researchers can then study how the light changes to determine what chemicals are inside the atmosphere. In the case of GJ 436b, however, it was more about what chemicals were not there.

“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,” explained Heather Knutson of the California Institute of Technology. “Instead of hydrogen, it could have relatively large amounts of heavier molecules such as water vapor, carbon monoxide, and carbon dioxide, which would compress the atmosphere and make it hard for us to detect any chemical signals.”

The results couldn’t be more different in the GJ 1214b exoplanet, which is classified as a super-Earth. Researchers from the University of Chicago used the Hubble telescope to study the bloated sphere around this exoplanet and several cloud-like objects blanketing it. “You would expect very different kinds of clouds, to form on these planets than you would find, say, on Earth,” said study leader Laura Kreidberg. The research team couldn’t exactly determine what types of chemicals the clouds were made out of, but they did rule out water vapor, methane, nitrogen, carbon monoxide, and carbon dioxide.

These two groups of scientists will conduct more research now to better understand the atmosphere of the exoplanets, but in that time, they will use a more powerful telescope called the James Webb Space Telescope. “[It] will be transformative,” expressed Kreidberg. “The new capabilities of this telescope will allow us to peer through the clouds on GJ 1214b and similar exoplanets.”

Images courtesy of Space Telescope Science Institute.