(ORDO NEWS) — Astronomers at the University of California at Los Angeles have solved the mystery of the length of the day on Venus, whose rotation period could not be accurately determined for a long time, as well as the tilt of its axis and the size of the core.
New radar measurements taken from 2006 to 2020 show that on average, a day on Venus lasts 243.0226 Earth days, about two-thirds of an Earth year.
At the same time, the speed of rotation of Venus is always changing: a new measurement will give a result that will be slightly more or less than the previous one. The difference is at least 20 minutes. This explains the strange discrepancies of past measurements.
The reason, most likely, is the heavy atmosphere of Venus, which exchanges impulses with the surface of the planet.
On Earth, a similar process leads to a change in the length of the day by only a millisecond. On the second planet from the Sun, the mass of the atmosphere is 93 times greater than that of the Earth.
Venus’s axial tilt is exactly 2.6392 degrees (Earth is tilted by about 23 degrees), ten times the accuracy of previous estimates.
The axis precession cycle takes 29 thousand years. Based on these data, the team calculated that the planet’s core is about 3,500 kilometers across, although it is not yet known whether it is liquid or solid.
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