Gigantic, bow-shaped wave spotted in Venus’ atmosphere

Enlarge / Venus, as seen by the Akatsuki spacecraft, displaying the bow-shaped feature. Lighter colors reflect higher light emissions; the white regions are about 233 Kelvin. (credit: ©Planet-C)

The Akatsuki spacecraft arrived in orbit of Venus in December 2015, and it quickly captured a very strange feature: an atmospheric disturbance in the shape of a bow. The feature is enormous, stretching from the planet’s north pole to its south (10,000 kilometers, or 6,200 miles in total), and it's visible in both infrared and (dimly) ultraviolet light.

Images from this mission were recently released, and researchers have had the chance to review them and do some science. They’ve concluded that the mysterious structure is probably a gravity wave, caused by mountains on the surface and propagating up into the atmosphere. It’s “the only reasonable interpretation,” according to a new paper on the feature.

Gravity waves—not to be confused with gravitational waves, the kind recently observed by LIGO—are waves in a fluid, like water or air, caused by gravity. When some of the fluid is displaced upwards, gravity tries to correct it and restore equilibrium, a process that creates waves. The Earth’s atmosphere also has gravity waves created by the influence of mountains, which displace air upwards.