Atmospheric Peculiarity Earth Shares With Other Planets Can Help Identify Habitable Worlds

Atmospheric peculiarities similar to Earth and a few other planets may also be common to billion other planets and moons in the galaxy, researchers find. 

Seems like Earth, Jupiter, Uranus, Saturn and Neptune are not the only celestial bodies that experience air growing colder and thinner with altitude. Researchers of a new study found that this may be the case in other planets too, making it easier for researchers to find other habitable worlds, according to a press release.

In 1902 a scientist named Léon Teisserenc de Bort coined the term "tropopause," further leading to the introduction of terms like "stratosphere" for the atmosphere above, and "troposphere" for the layer below. More than 72 years later researchers discovered that "tropopause" existed in a few other planets like Jupiter, Saturn, Uranus and Neptune, as well as Saturn's largest moon, Titan. Moreover, they also found that the "troposphere" changed into the "stratosphere" at roughly the same level as on Earth.

In this new study, UW astronomer Tyler Robinson and planetary scientist David Catling further explain why this division takes place and how it may be common to billion other planets and moons throughout the galaxy.

"The explanation lies in the physics of infrared radiation," said Robinson. "Atmospheric gases gain energy by absorbing infrared light from the sunlit surface of a rocky planet or from the deeper parts of the atmosphere of a planet like Jupiter, which has no surface."

Using analytical models, scientists of the study were able to determine that the atmosphere becomes "transparent to thermal radiation" at high altitudes with lower pressure. When the pressure reaches 0.1 bar, infrared radiation causes the atmosphere to heat up.

The information provided from this study can be used to study climatic conditions of other planets.

"Then we have somewhere we can start to characterize that world," Robinson said. "We know that temperatures are going to increase below the tropopause, and we have some models for how we think those temperatures increase - so given that leg up, we can start to extrapolate downward toward the surface. It's neat that common physics not only explains what's going on in solar system atmospheres, but also might help with the search for life elsewhere," he said.