Atmospheric Haze Replicated in Laboratory To Help Detect Exoplanet With Earth-Like Conditions

One of the James Webb Space Telescope's main tasks is scanning exoplanets' atmospheres to look for signs of habitability. It is known that water is necessary for life, so detecting the presence of water in and around extraterrestrial worlds has become a high priority for planetary scientists.

However, getting a clear view of the exoplanets' secrets can be difficult due to the presence of haze or clouds that make the atmosphere opaque. Organic hazes of different chemical compositions lurking in the skies of distant worlds could affect our ability to detect water and other signs of life.

What is an Atmospheric Haze?

Atmospheric haze is a suspension of dry dust particles, aerosols, or smoke. Here on Earth, the formation of haze can be brought about by volcanic activity, windy weather, and man-made activities. In other planets, such as Uranus, haze can be formed from the stagnant, sluggish atmosphere.

Various levels and types of haze can influence how the particles spread out through a planet's atmosphere. As a result, the data gathered by telescopes about distant planets can be altered. Whether a planet's atmosphere contains haze or other particles could influence surface temperatures, incoming levels of starlight, and other factors hindering or promoting biological activity.

Simulating Hazy Conditions

Water is the first thing scientists look for when determining the habitability of a distant planet, and there have been studies that confirm the presence of water in exoplanet atmospheres. In the study "Optical properties of organic haze analogues in water-rich exoplanet atmospheres observable with JWST," the modeling suggests that these exoplanets most likely also contain haze.

Experts at Johns Hopkins University have attempted to recreate conditions conducive to producing hazy atmospheres on alien planets. Their simulations could help them identify and model the formation and evolution of water in exoplanet atmospheres.

The researchers were specifically interested in the effects of these hazes on the optical properties of spectra emitted from exoplanets that contain water in their atmospheres. Led by planetary scientist Chao He, the team conducted experiments in a customized chamber to observe the formation of hazes on watery planets. They also investigated how they might distort observations of the existence of crucial substances in exoplanet's atmospheres.

He and his colleagues created two gas mixtures of water vapor and other compounds believed to be shared among exoplanets. Then, they subjected the gas to ultraviolet light to mimic the effect of light from a nearby star on the chemical reactions of gas in the exoplanet's atmosphere. The team measured how light interacted with particles in the chamber from the data collected, getting better insights into how the haze might influence exoplanet spectra.

The collected data matched the chemical signature of a well-studied exoplanet called GJ 1214 b. This points to the fact that organic haze may skew the observations made on various planet's atmospheres.

Researchers are aware that there are various exoplanets with differing atmospheric chemical compositions. For this reason, they plan to create more lab-made haze "analogs" to understand their influence on planetary observations taken from Earth.