There are thousands of exoplanets that have been discovered without alien life, but a new study suggests that scientists have been searching for the wrong attributes.
What About Exoplanets Was Discovered?
A new theory dictates that alien life on exoplanets can be detected by simply examining the atmospheric changes during the seasons. The composition of the gases within the atmospheres would be what researchers can search for.
A study outlining this procedure was published on May 9 in The Astrophysical Journal Letters.
"A potentially powerful way to assess exoplanets for inhabitation would be to observe their atmospheres throughout their orbits to see if we can detect changes in these biosignature gases over the course of a year," said study author Stephanie Olson, a scientist at the University of California-Riverside. "Atmospheric seasonality is a promising biosignature because it is biologically modulated on Earth and is likely to occur on other inhabited worlds."
On Earth, the tilted axis causes seasonal changes. During the summer, there is an increase in oxygen and a decrease in carbon dioxide in the northern hemisphere's atmosphere due to the plant growth. It is possible for another exoplanet's atmosphere to exhibit this trait if there is life.
Thousands of exoplanets that exist within a habitable zone have been discovered, but they are many light-years away. Thankfully, modern telescopes such as PLATO can show the atmospheric changes on the exoplanets.
How Did Scientists Know How To Study Climate As A Way To Find Aliens?
Spectroscopy, which is the study of how light interacts with matter, is what Olson's team suggests can be used to detect seasonal changes on the atmospheres of exoplanets.
To test the theory, the researchers built a model of a planet with a similar chemical composition to Earth billions of years ago. They discovered that the ozone layer of the planet would be a better indicator of seasonal changes than just by looking at the chemicals on the planet. The team suggests studying the exoplanet for a full year before determining if it has seasonal changes.
Problems With Looking At Seasonal Changes
Although this theory could work, there are some flaws with it. First, in order to study the ozone of an exoplanet, the telescopes would need ultraviolet capabilities. Even if gases such as methane and oxygen are found on an exoplanet, that doesn't necessarily mean that there is life on it because it could be a false positive.
In the end, even if the theory does not find alien life, it is a good way to test which planets are similar to Earth.