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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: 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