Submitted via IRC for BoyceMagooglyMonkey
Time is out of joint on Venus. The planet's thick air, which spins much faster than the solid globe, may push against the flanks of mountains and change Venus' rotation rate.
Computer simulations show that the thick Venusian atmosphere, whipping around the planet at 100 meters per second, exerts enough push against a mountain on one side and suction on the other side to speed the planet's rotation rate by about two minutes each Venus day, according to a study in Nature Geoscience June 18.
That's not much, considering that the planet rotates just once every 243 Earth days. By comparison, Venus' atmosphere rotates about once every four Earth days. Precise measurements of the planet's rotation rate have varied by about seven minutes, however. The push and pull of the air over the mountains could help explain the mismatch, with some other force — possibly the gravitational influence of the sun — slowing the planet's spin back down.
Source: Venus’ Thick Atmosphere Speeds Up the Planet's Spin
(Score: -1, Spam) by Anonymous Coward on Wednesday June 20 2018, @10:37PM (1 child)
Venus is pretty much the white person of planets; slow rotation, windy, and influenced by the sun.
(Score: -1, Spam) by Anonymous Coward on Wednesday June 20 2018, @11:02PM
So, there's that.
(Score: 0, Troll) by Anonymous Coward on Wednesday June 20 2018, @10:59PM (3 children)
Perhaps they are being driven by an electric current. [youtube.com]
(Score: 2) by frojack on Thursday June 21 2018, @12:37AM (2 children)
Hmmm, by his own admission he seems to be the only person who believe this Electric Current theory.
But be that as it may, why would it be increasing about 33%
Not much has changed in the vicinity of Venus over the time we've been observing it, so this degree of an increase in 10 years would have the atmosphere reaching escape velocity had it gone on for 100 or 1000 years.
His theory shows no indication of the electric current being variable, so its unlikely to be the source of the speed up.
No, you are mistaken. I've always had this sig.
(Score: 2) by aristarchus on Thursday June 21 2018, @06:05AM
C'mon, frojack! The Electric Universe people are the homeopaths of astrophysics! You of all people, or at least electrostatic entities, should recognize this!
(Score: 0) by Anonymous Coward on Thursday June 21 2018, @12:08PM
So, perhaps, there is a natural regulating mechanism that keeps the rotation from becoming too ridiculous.
(Score: 1, Interesting) by Anonymous Coward on Wednesday June 20 2018, @11:39PM (12 children)
Can somebody who knows astronomy or meteorologist or whatever help explain what is going on to a layman like me?
If the wind is speeding up the planet's rotation, that suggests that the wind must be moving faster than the rock underneath it. However, I had always understood the wind to be an effect of the planet's rotation itself caused by reasons (... uhh... maybe asymmetric heating caused by the sun only hitting half of the rotating planet?). So how could the wind be rotating faster than the planet underneath, and how does this not violate Conservation of Energy?
(Score: 2) by unauthorized on Thursday June 21 2018, @12:25AM (8 children)
IANAA, but I do know that solar radiation adds energy to the system, there is no violation of the conservation of energy there.
(Score: 2) by frojack on Thursday June 21 2018, @12:50AM (6 children)
Well, lets assume it is from energy supplied by the sun.
What mechanism causes it to rotate the planet's atmosphere? (Not expecting an answer - the scientists admit they don't know).
Secondly, why (after millions of years of solar input) is the wind and the planet ONLY rotating as fast as it is? After all if the wind is enough speed the planet’s rotation rate by about two minutes each Venus day, that should be substantial. It is clearly over powering the tidally locked planet's solid core (gravity slow-down).
When you view these things over eons, with a steady solar input, you would expect the atmosphere to have come to some sort of stable state by now.
No, you are mistaken. I've always had this sig.
(Score: 3, Interesting) by unauthorized on Thursday June 21 2018, @01:37AM (5 children)
Sorry, I should have worded that more clearly. What I meant to say is that the law of conservation of energy applies only to closed systems, but Venus is not a closed system because it's getting energy from the Sun, and therefore not a closed system.
That's quite easy actually, the planet not only takes energy from the sun but radiates it into space as electromagnetic radiation. When gas molecules receive energy, they become excited they start moving faster and faster, which results in more collisions and greater collision velocity, which in turn slows down the molecules and releases electromagnetic radiation proportional to the kinetic energy lost. At some point, the input and output of energy reaches equilibrium since the planet is only getting a relatively consistent input of solar flux, whilst radiation increases with the amount of energy within the system.
(Score: 3, Interesting) by FatPhil on Thursday June 21 2018, @01:05PM (4 children)
If I was the scientists, I'd be tempted to tap the dials and double-check those readings. Even dark matter is a mechanism to explain galactic orbit anomalies, this anomaly doesn't even have a mechanism that can explain it.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2, Disagree) by unauthorized on Thursday June 21 2018, @02:01PM (3 children)
The law of conservation of angular momentum only applies to closed systems, which Venus is not. You are also forgetting solar wind which does have mass and therefore momentum.
(Score: 2) by FatPhil on Saturday June 23 2018, @03:50PM (2 children)
And the solar system is effectively a closed system in this regard.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2, Disagree) by unauthorized on Sunday June 24 2018, @07:59AM (1 child)
It's not a closed system. A closed system in mechanics must not receive external matter or force, which is not true for Venus. Torque can arise from both linear momentum and heating up matter.
Only under highly idealized circumstances which don't really arise in macroscopic systems. For linear force to not affect torque, either the angle between the positional and force vector must be such that sin(angle)=0 (ie equal to pi), or their cross product must result in a zero-length vector.
In other words, solar wind only does not affect the rotational force when hits the atmosphere in such a way that the force applied is exactly perpendicular to the angular momentum vector. This is impossible for a diffuse stream of particles.
(Score: 2) by FatPhil on Sunday June 24 2018, @09:39AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1, Funny) by Anonymous Coward on Thursday June 21 2018, @02:04AM
> IANAA
You sure SOUND like an aardvark.
(Score: 3, Insightful) by deimtee on Thursday June 21 2018, @07:11AM (2 children)
Pretty sure that what the summary is claiming violates conservation of momentum.
Venus as a whole, including the atmosphere, has a certain amount of angular momentum. That isn't going to change unless a force that doesn't act through the centre of mass impinges on the planet.* If the atmosphere's rotation speeds up, due to local heating or whatever, then the solid planet will in fact slow down. The effect will be pretty small, massive as Venus's atmosphere is, it is still tiny compared to the mass of the planet. 2 to 7 minutes difference over a 5,832 hour day sounds about right for the change in wind speed that frojack quoted.
*The main one will be tidal drag which will be very small for a planet that rotates as slowly as Venus.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 0) by Anonymous Coward on Thursday June 21 2018, @10:50AM (1 child)
heating won't act on the center of mass.
due to local conditions the atmosphere may accept a different percentage of the energy input (which can be considered a constant times some factor that depends on "Sun's angle in the sky").
therefore the atmosphere can in principle be rotated by a feedback mechanism if the rotation emphasizes the conditions that lead to the initial differential heating.
I don't know if this is actually happening here (no time to read the paper), but a mechanism for differential heating does exist.
(Score: 2) by deimtee on Thursday June 21 2018, @12:45PM
The point was that there is no mechanism postulated to change the total angular momentum of the planet. If the atmosphere speeds up for any reason that doesn't involve an interplanetary force, then it must have been by reaction against the planet. Newtons third law. Without an external force - not just an energy input - the atmosphere cannot accelerate without pushing back on something else. That something else is the planet.
If the wind is continually pushing against a mountain in one place, then it must be pushing against something else in the opposite direction somewhere else. Saying the wind can accelerate the planet is as valid as saying that if you pull on your boots hard enough you can lift yourself off the ground.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 0) by Anonymous Coward on Thursday June 21 2018, @12:14AM
I thought the rotation period was in a resonance relationship between the Sun and Earth. It was kind of a round-about relationship if I remember (no pun intended). Such relationships are often stable for long periods of time, requiring a fairly significant force to knock it out of resonance, at which point bodies often drift into a new resonance fitting closer to the various forces it experiences. It's sort of like a grove in a non-spiral vinyl record: it takes a big jolt to knock the needle into a different grove.
(Score: 0) by Anonymous Coward on Thursday June 21 2018, @07:13AM
... if we keep pumping shit into the atmosphere, our days will start getting shorter?
(Score: 2) by wisnoskij on Thursday June 21 2018, @10:15AM
So every Earth year it speeds up by 2 minutes (1/262800 or a rotation). So even if it started at rest, the planet has had several thousand times more than enough time to become the fastest rotating planet in the solar system.