Recorded by the Japanese meteorological satellite Akatsuki in December 2015, the huge pressure wave spanned 10,000 kilometres across both hemispheres of Venus, nearly from pole to pole. Usually clouds in that region move at about 100 meters (328 feet) per second, whereas this cloud is stationary compared to the planet's rotation. It's like the water of a stream flowing over a rock, making a ripple, explains Colin Wilson, an atmospheric scientist at Oxford University who was not involved in the paper. The centre of the wave was directly above the western slope of the Aphrodite Terra highlands. Venus' upper atmosphere is always covered in a thick layer of cloud made up of sulphuric acid, which move at speeds of 100m/s.
'When a gravity wave propagates in an atmosphere, air parcels vertically oscillate by a balance of buoyancy and gravity forces, ' lead author Makoto Taguchi told MailOnline.
The wave was captured by JAXA's Akatsuki spacecraft as it appeared like a bright spot in the images, the European Space Agency have stated that these waves are found in Earth's atmosphere as well.
It is believed that the giant wave was caused by the gravity of the mountains present on the surface of Venus, as scientists think these towering mountains are the key reason to creating these bows.
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The super-rotation of Venus' atmosphere makes it very different from Earth. Any features spotted in the atmosphere should get carried along by the fierce winds, but this curved wave remained planted firmly in place, lasting for at least four days.
The team hopes to address that question with further observations of the planet, and with that insight, we might finally be able to answer an even bigger question - how did Venus' insane super-rotation occur? According to scientists, the wave was observed for a few days, before it suddenly disappeared.
As such, the team say that the evidence is pointing towards gravity waves. Essentially, airflow passing over Venus's mountains was sculpted into waveforms that propagated upward, eventually taking the bow-shape observed by Akatsuki. The atmosphere of Venus now is principally carbon dioxide, which is the reason the surface is extremely hot. "We suggest that winds in the deep atmosphere may be spatially or temporally more variable than previously thought", the newly published study in nature.com stated. The atmosphere shields Venus from view and makes it hard to understand it. Although it's sometimes described as Earth's "twin", being rocky like Earth and of a similar size and mass, it's also wildly different.
The Japanese spacecraft swung into orbit around Venus in December 2015 and snapped pictures of the wave until the observations were cut short to allow mission controllers to work on the spacecraft's trajectory and communications.