Science & Technology
"When the two maps did not align, I first thought there was a mistake in my calculations as Magellan measured the value very accurately, but we have checked every possible error we could think of," said Nils Müller, a planetary scientist at the DLR German Aerospace Centre, lead author of a research paper investigating the rotation.
Using the VIRTIS infrared instrument, scientists discovered that some surface features were displaced by up to 20 km from where they should be given the accepted rotation rate as measured by the Magellan orbiter in the early 1990s.
Over its four-year mission, Magellan determined the length of the day on Venus as being equal to 243.0185 Earth days. But the data from Venus Express indicate the length of the Venus day is on average 6.5 minutes longer.
What could cause the planet to slow down? One possibility may be the raging weather on Venus. Recent atmospheric models have shown that the planet could have weather cycles stretching over decades, which could lead to equally long-term changes in the rotation period. The most important of those forces is due to the dense atmosphere - more than 90 times the pressure of Earth's and high-speed weather systems, which are believed to change the planet's rotation rate through friction with the surface.
Earth experiences a similar effect, where it is largely caused by wind and tides. The length of an Earth day can change by roughly a millisecond and depends seasonally with wind patterns and temperatures over the course of a year.
But a change of 6.5 minutes over a little more than a decade is a huge variation.
Other effects could also be at work, including exchanges of angular momentum between Venus and the Earth when the two planets are relatively close to each other. But the scientists are still working to figure out the reason for the slow down.
These detailed measurements from orbit are also helping scientists determine whether Venus has a solid or liquid core, which will help our understanding how the planet formed and evolved. If Venus has a solid core, its mass must be more concentrated towards the center. In this case, the planet's rotation would react less to external forces.
"An accurate value for Venus' rotation rate will help in planning future missions, because precise information will be needed to select potential landing sites," said Håkan Svedhem, ESA's Venus Express project scientist.
Venus Express will keep monitoring the planet to determine if the rate of rotation continues to change.
Reader Comments
The approach of something? Highly unlikely as far as the inner solar system goes. However it is quite likely there is a large gas or ice giant in the Oort Cloud or beyond that's eccentric orbit may be responsible for the periodic extinction events. But one must remember as we orbit the Center of the Galaxy the solar system does enter into density waves at the arms of our galaxy. Right now we are enjoying a rather calm moment as we are in between these traffic jam areas. If we were in an arm or approaching we would see an enormously large amount of stars in our sky. They are busy with stars.
When orbiting objects are at extreme distances to each other they become tidally locked to one another (example when the moon formed it was very close to earth and became tidally locked-from Earth we only see one side of the moon. That would have likely not been so were it captured and at a greater distance than it's birth distance and we'd have a rotating moon. Perhaps Venus' distance to the moon is slowing its rotation down. However it could very well be the drag of that horrifically dense atmosphere.
Food for thought.
...that can and must be done. However, if I had to guess, I'd say you are not presently in a frame of mind to profitably engage in discussions about what can or ought to be done. Godspeed.
If you have views on "There is much that can and must be done" then I would love to hear them as a differing point of view with a well thought out rebuttal is a good way to change an apposing view. Your assumption on others frame of mind appears to be just an excuse to avoid a situation or explanation.
Interestingly the word godspeed refers to a greeting that was an approval of the course being pursued by the one being greeted.
I realize the article didn't give many details. It definitely didn't give enough detail as to why they think the rotation is slowing.
I could see if they had monitored the entire map, and having seen is shifted by x over the past decade, but it didn't say that. It only referred to some features. How do they know the land on Venus doesn't just normally shift in ways we don't see on Earth? They deduced a reduction in rotation speed because things weren't where they expected them to be. That doesn't sound like a direct measurement.
[Link]
"The most commonly cited figure for Saturn's rotation period - 10 hours, 39 minutes and 22.4 seconds - was derived in 1980 from Voyager observations of radio waves generated by solar radiation hitting the planet's atmosphere. Yet Cassini has returned a result almost 8 minutes longer, a difference that defies easy explanation."
Most interesting that the rotation of both Venus and Saturn appears to have slowed by a similar amount: 6.5 minutes in the case of Venus, and 8 minutes in the case of Saturn.
Something wicked this way comes https://www.sott.net/article/142651-Something-Wicked-This-Way-Comes ??
https://www.sott.net/article/142651-Something-Wicked-This-Way-Comes
The statement in this article - " If Venus has a solid core, its mass must be more concentrated towards the center. In this case, the planet's rotation would react less to external forces. " is just plain Wrong.
A heavy core would give the overall body a lower resistance to change in rotation rate. This is basic physics. I find it very disturbing to see such an error in a supposedly scientific publication.
...was crystal clear n your initial post; it still is. So this...
"Your assumption on others frame of mind appears to be just an excuse to avoid a situation or explanation."
...is so much nonsense. If you truly desire to know what I think, all you have to do is ask -- sincerely. So far, your arrogant, childish attitude is palpable and I will not waste my time satisfying your curiosity. Cheerio!
the first readings where simply in error? why is that not an option? Space agencies arent immune to mistakes, technical failure and just plain being wrong in interpreting data: perhaps one set of data is inaccurate, and venus isnt slowing at all.
Perhaps there is an object of notable mass and magnetism approaching? Something affected Saturn in a way that is not easy. Something is affecting us, too, and every effect must have a proportionate cause.