A bow/wave-shaped "structure" in the atmosphere of Venus has been observed by the Akatsuki spacecraft. It has been called the result of an "atmospheric gravity wave":
A giant wave in the atmosphere of Venus may be the biggest of its kind in the Solar System. The feature, observed by a Japanese spacecraft, is thought to be generated in a broadly similar way to the surface ripples that form as water flows over rocks on a stream bed. In this case, the wave is thought to form as the lower atmosphere flows over mountains on Venus' surface.
The findings are published in Nature Communications journal [DOI: 10.1038/ngeo2873] [DX]. Just after entering orbit around Venus in 2015, the Akatsuki orbiter observed a bow-shaped feature in the upper atmosphere over several days. Curiously, the bright structure - which stretched for 10,000km - remained stationary at the altitude of Venus' cloud tops. This is difficult to reconcile with what we know about Venus' thick upper atmosphere, in which clouds streak by at 100 metres per second (m/s).
(Score: 0) by Anonymous Coward on Tuesday January 17 2017, @04:45PM
Cowabunga, venusian dudes!
(Score: 0) by Anonymous Coward on Wednesday January 18 2017, @12:13AM
Is it bad I heard this in my head in the very distinct voices of the ninja turtles?