The mysterious discrepancies in the measurements of the length of the day on Venus turned out to be connected with a giant "standing wave" in the atmosphere of Venus, recently discovered by the Akatsuki probe. As scientists have found, it periodically spins and slows down the planet, according to an article published in the journal Nature Geoscience.
Venus, despite its almost "terrestrial" size and chemical composition, is one of the most unusual planets in the solar system. Its superdense atmosphere, heated to "hellish" temperatures, rotates 60 times faster than the planet itself, which generates super-powerful winds moving at a speed of 500 kilometers per hour, and a day on it lasts longer than a year - 240 and 224 Earth days …
Astronomers have been trying for a long time to understand what is connected with such a slow rotation of Venus around its axis. Some scientists believe that this may be due to the fact that in the distant past, like Uranus and Mercury, it collided with a large asteroid, which slowed down the planet and "flipped" its axis, forcing it to rotate around itself in the "wrong" direction.
This idea, as noted by Thomas Navarro of the University of California at Los Angeles (USA), contradicts data from satellites that have studied Venus at different times. Their observations show that some unknown phenomenon continues to "slow down" the planet and that the length of the day on it increases by 6-7 minutes every Venusian "day".
Such discrepancies make many planetary scientists believe that the main "brake" of Venus's rotation was not an asteroid, but its "supersonic" atmosphere. According to the supporters of this idea, its movement and friction against the surface of the second solar planet slowed it down and continues to slow it down, which is reflected in the discrepancies in the length of the day measured by the Magellan and Venus-Express probes.
Navarro and his colleagues found out what caused such discrepancies in the probe measurements by studying another curious mystery of Venus - the mysterious "standing wave" 10 thousand kilometers long, discovered by the Akatsuki probe immediately after its arrival in Venus orbit in early 2016.
Such waves, Navarro explains, usually occur in the earth's atmosphere over long and high mountain ranges, and last for a relatively short time. There are no large mountains on Venus, and the wave found by the Japanese automatic station is not going to disappear to this day, which made scientists wonder how it could have arisen.
To answer this question, Navarro and his team created a computer model of the planet's atmosphere that takes into account all the large irregularities that exist on its surface. These calculations unexpectedly showed that "eternal" standing waves can occur during the day in four regions of Venus, where there are low elevations and mountain ranges, and disappear after several Earth days at night.
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Observing the formation of these waves, scientists noticed that they had to influence the rotation of the planet around its axis in a special way, slowing it down at night and accelerating it during the day. The same calculations showed that the planet is accelerating more than it is slowing down, which explains why the measurements of the length of the day from "Magellan" and "Venus Express" differ from each other.
