20:08 18 January 2017
A massive wave in the atmosphere of Venus, which could be the biggest of its kind in the Solar System, has been observed by a Japanese spacecraft.
The giant wave is believed to have been generated in a broadly similar way to the surface ripples that form as water flows over rocks on a stream bed.
The Akatsuki spacecraft entered Venus’ orbit in 2015 and has observed a bow-shaped feature in the upper atmosphere over several days. Scientists showed that the bright region, which was hotter than surrounding parts of the atmosphere, was fixed over a mountainous region of the surface known as Aphrodite Terra.
Dr Colin Wilson, a planetary scientist from the University of Oxford, who was not involved in the study, explained: "If you have a stream and it's flowing over a rock, you get the gravity waves propagating upwards through the water. At the surface of the stream, you will see it as changes in height.
"What's happening here is slightly different, because we're seeing it in cloud top temperatures. But the air particles are moving up and down, very much as the water particles are moving up and down."