“We don’t know what these atmospheres are made of,” said astronomer Alexander Rathke of the Technical University of Denmark. He said, “We have ideas and simulations and all that, but we don’t really know anything. We have to go and see.”
The James Webb Space Telescope, sometimes known as the JWST, may prove powerful enough to determine the specific components of exoplanet atmospheres because each type of particle absorbs different wavelengths of light.
But these discoveries depend on the weather on the exoplanets. The bright, reflective covering of clouds can prevent any starlight from entering the atmospheres of exoplanets, destroying any attempt to detect alien winds.
“It is very difficult to distinguish an atmosphere without clouds or an atmosphere,” Dr. Rathke said.
If the weather is cooperative, astronomers are particularly interested in knowing whether water is present in the atmospheres of exoplanets. At least on Earth, water is a basic requirement for life. “We think this would be a good starting point for the search for life,” Dr. Mansfield said.
But a watery atmosphere does not necessarily mean that an exoplanet harbors life. To confirm that a planet has life, scientists need to find a biosignature, molecule, or group of molecules that the organisms uniquely make.