Lab-cooked alien haze clears view to water-rich exoplanets

Scientists at Johns Hopkins have simulated conditions that allow hazy skies to form in distant water worlds - a crucial step that they say could help in the search for life beyond our solar system.

The research will help scientists model how water exoplanets (planets outside our solar system) form and evolve, findings that could help in the search for life beyond our solar system.

"The big picture is whether there is life outside the solar system, but trying to answer that kind of question requires really detailed modeling of all different types, specifically in planets with lots of water," said co-author Sarah Hörst, a Johns Hopkins associate professor of Earth and planetary sciences, adding that they are the first to determine how much haze can form in water planets beyond the solar system.

"Water is the first thing we look for when we're trying to see if a planet is habitable, and there are already exciting observations of water in exoplanet atmospheres. But our experiments and modeling suggest these planets most likely also contain haze," said Chao He, a planetary scientist who led the research at Johns Hopkins.

The team made a concoction of two gas mixtures containing water vapor and other compounds hypothesized to be common in exoplanets. Those concoctions were then beamed with ultraviolet light to simulate how light from a star would start the chemical reactions that produce haze particles.

In the next step, the team measured how much light the particles absorbed and reflected to understand how they would interact with light in the atmosphere.

The data matched the chemical signatures of GJ 1214 b, the first super-Earth around which an atmosphere has been found, more accurately than previous research, demonstrating that hazes with different optical properties can lead to misinterpretations of a planet's atmosphere.

The researchers are now working to create more lab-made haze analogs with gas mixtures that more accurately represent what they see with telescopes. Their findings are published in the journal Nature Astronomy.