Unlike Earth, the gases in Venus’ atmosphere aren’t uniformly mixed
A new look at the nitrogen on Venus may overturn a decades-old assumption about the planet’s atmosphere. Scientists long thought that atmospheric turbulence would create a uniform mixture of gases in Venus’s atmosphere below an altitude of about 100 kilometers. That’s how it works on Earth. But data from NASA’s MESSENGER spacecraft now indicate that this part of Venus’ atmosphere contains layers of gas with different nitrogen concentrations, researchers report online April 20 in Nature Astronomy. The unexpected stratification of Venus’s atmosphere may serve as a cautionary tale for astronomers analyzing the atmospheres of planets around other stars, says Patrick Peplowski, a physicist at Johns Hopkins University Applied Physics Laboratory in Laurel, Md. The new results suggest that observations of a planet’s upper atmosphere from afar don’t necessarily reflect conditions closer to the surface. Peplowski and colleagues analyzed measurements of neutrons escaping from Venus’ atmosphere made by MESSENGER as it flew by the planet in 2007. Neutrons are produced by galactic cosmic rays hitting...