An atmospheric peculiarity the Earth shares with Jupiter, Saturn, Uranus and Neptune is likely common to billions of planets, University of Washington astronomers have found, and knowing that may help in the search for potentially habitable worlds.

First, some history: It’s known that air grows colder and thinner with altitude, but in 1902 a scientist named Léon Teisserenc de Bort, using instrument-equipped balloons, found a point in Earth’s atmosphere at about 40,000 to 50,000 feet where the air stops cooling and begins growing warmer.

He called this invisible turnaround a “tropopause,” and coined the terms “stratosphere” for the atmosphere above, and “troposphere” for the layer below, where we live — terms still used today.

Then, in the 1980s, NASA spacecraft discovered that tropopauses are also present in the atmospheres of the planets Jupiter, Saturn, Uranus and Neptune, as well as Saturn’s largest moon, Titan. And remarkably, these turnaround points all occur at roughly the same level in the atmosphere of each of these different worlds — at a pressure of about 0.1 bar, or about one-tenth of the air pressure at Earth’s surface.

Now, a paper by UW astronomer Tyler Robinson and planetary scientist David Catling published online Dec. 8 in the journal Nature Geoscience uses basic physics to show why this happens, and suggests that tropopauses are probably common to billions of thick-atmosphere planets and moons throughout the galaxy.

Read more on the UW Today website.

EarthTropopause from Space Station
NASA Johnson Space Center
NASA Johnson Space Center