Scientists believe that Venus takes an average of 243 Earth days to complete one full rotation and this rotation rate varies. As Venus spins at different speeds, the length of a day varies on the planet. Until now scientists weren’t able to clearly explain the reason why the rate changes. But a new study has found that Venus’s rotation rate is accelerated by the planet’s thick atmosphere and the speed at which it moves.
Researchers from UCLA and University of Paris-Saclay in France used the images captured by the Japanese space agency images JAXA’s Akatsuki spacecraft in 2015 to develop a new planetary model. They found that the interaction between Venus’ fast-moving atmosphere and its surface, marked with volcanos and mountains, changes the planet’s spinning speed. The Akatsuki spacecraft is currently in orbit around Venus.
While investigating a 10,000-kilometer-long wave in Venus’s cloud tops, the scientist found that when the atmosphere—traveling at 100 meters per second—hits mountains on Venus’s surface, it results in an event called a “gravity wave”, which creates enough push and pull to alter the planet’s rotation, thereby changing the length of a Venusian day by up to two minutes.
“It was very surprising to find this wave that was not moving with the super-rotating atmosphere but instead it was moving with the surface,” said Thomas Navarro, study author, and researcher at the University of California. “Overall, a net force is exerted on the mountain, and the whole solid body follows.”
Dr. Navarro added that more research is needed to pin down the study results even further. The research team is hopeful that studying the waves and how they affect Venus could help them better understand the planet’s interior, as well as its strange atmosphere. The information will also likely help scientists learn about other weather-related issues on Earth.
The study findings were published in Nature Geoscience.