The atmosphere of Venus slows down and accelerates the planet

Employees of the University of California received high-precision data on the rotation of Venus around its axis. It turned out that this rotation occurs at different speeds – the Venusian day lasts sometimes faster, then slower, deviating from the average value by up to 10 minutes in both directions.

This is how the rotation of the planet is affected by its very dense and heavy atmosphere.

For 15 years, scientists irradiated Venus with radio waves from the 70-meter antenna of the Goldstone Observatory and received the reflected signal. According to Jean-Luc Margot, head of research, the planet was used as a giant disco ball, which reflects light rays in different directions with its irregularities. Only instead of visible light, a powerful stream of radio waves was directed at Venus.

Based on the reflection of the signal from the unevenness of the Venus landscape, scientists obtained the most complete data on the rotation of the planet around its axis. On average, a day on Venus lasts 243.0226 Earth months—about eight Earth months. The slow rotation of the planet has been known for a long time, but scientists for the first time determined the time of the "day" change so accurately.

For researchers, large fluctuations in the length of the day on Venus came as a surprise: this may become an important factor for future flights to the planet. Due to a difference of 20 minutes, the descending devices can miss the intended landing sites by as much as 30 kilometers.

The reason for such inconsistency during the day turned out to be the atmosphere of Venus. It is 93 times heavier than Earth's, and the pressure on the surface of the planet can be compared with the pressure of water at a depth of 900 meters on Earth. When the wind blows in the direction of Venus' rotation, it accelerates it, and when it blows against it, it slows it down. It is also the Earth, but the Earth's day changes only by a thousandth of a second because of it.

As Jean-Luc Margot pointed out, it was not easy to conduct the research – radar at such distances requires high accuracy of guidance. But the results of the observations met all expectations, so now a team of scientists is preparing to study Jupiter's moons Europa and Ganymede in a similar way.