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 Post subject: Venus Spinning Slower
PostPosted: Fri Feb 24, 2012 1:28 pm 
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Venus Spinning Slower Than Thought—Scientists Stumped
Mysterious decrease could affect future exploration missions.

Jason Major
for National Geographic News
Published February 14, 2012

Planet lovers take note: Venus is spinning even slower than astronomers thought, according to new data from a European space probe.

In the early 1990s scientists with NASA's Magellan mission calculated that a single rotation of Venus takes 243.015 Earth days, based on the speed of surface features passing beneath the orbiting spacecraft.

But scientists now mapping Venus's surface with the European Space Agency's Venus Express orbiter were surprised to find the same features up to 12.4 miles (20 kilometers) from where they were expected to be, based on the previous measurements.

According to the new data, Venus is rotating 6.5 minutes slower than it was 16 years ago, a result that's been found to correlate with long-term radar observations taken from Earth.

"When the two maps did not align, I first thought there was a mistake in my calculations, as Magellan measured the value [of Venus's spin] very accurately," Nils Müller, a planetary scientist at the DLR German Aerospace Centre, said in a statement.

"But we have checked every possible error we could think of."

Planet Slowed by Dense Atmosphere?

One possible cause for the slowed spin is friction caused by Venus' thick atmosphere and high-speed winds. The motion of the atmosphere on Earth, for example, has been observed to affect the planet's rotation rate, albeit to a much smaller degree.

Thanks to a heavy blanket of carbon dioxide-laden air, the surface pressure on Venus is 90 times what we experience on Earth at sea level, and opaque clouds of caustic sulphuric acid constantly whip around the planet at hurricane speeds.

Still, "it is difficult to find a mechanism that will cause the average rotation rate to change this much in only 16 years," Venus Express project scientist Håkan Svedhem told National Geographic News.

"The origin of this could lay in the solar cycle or in long-term weather patterns that modify the atmospheric dynamics. But this puzzle is not yet solved."

Some reports cite an exchange of angular momentum between Venus and Earth as a possible cause for the variation. A moon, for example, can cause a planet to rotate slower than expected, because both objects share angular momentum.

But with 23.6 million miles (38 million kilometers) between the two planets at their closest approach, "there is no exchange of momentum between Venus and the Earth," Svedhem stated.

Instead, he said, further study is needed to discern the cause—or causes—of Venus' slight reduction in speed.

Ultimately, he added, it's important to know exactly how fast the planet is spinning, since any possible future missions to explore Venus will need precise information to chose their landing sites.

http://news.nationalgeographic.com/news/2012/02/120214-venus-planets-slower-spin-esa-space-science/

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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 2:33 am 
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Is it true also that Earth slowed down to ? , of late , lsol

edit eart to earth

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Last edited by aianawa aianawa nui on Sat Feb 25, 2012 10:24 am, edited 1 time in total.

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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 5:06 am 
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Speed of Earth's Rotation Slowing?
I heard that the rate of Earth's spin is decreasing. How much is the Earth slowing down? Has it always been slowing down? Ask an Astrophysicist said that the Earth spins like a figure skater, but they can only spin for so long!

The Earth's spin is slowing down by about 1.5 - 2 milliseconds per century, and that angular momentum is moving into the Moon's orbit, which is getting larger. The reason for this, and the reason a figure skater can only spin for so long, is friction. In the case of the skater, it's air resistance and friction with the ice. In the case of the Earth, it's the friction due to tides moving around the Earth.

Dr. Eric Christian
(June 2000)


Moon Leaves Earth's Gravity?
Will the Moon leave the Earth's gravity?

The Moon will not leave the Earth's gravity, even though the orbit of the Moon is increasing slightly. The Earth's rotation is slowing down (due to "tidal braking"), and to conserve angular momentum the Moon is accelerating. The Moon's orbit increases by about 3 cm/year.

The Earth and the Moon eventually will be "locked" together with each only having one side constantly facing the other. (Right now the same side of the Moon faces the Earth, but all sides of the Earth see the Moon. In the future this will not be true!) Life on Earth will be quite different then, but this won't occur for billions of years yet. When it does occur, the Moon's orbit will be 50% larger than it is now, and a month will be about 50 days.

Dr. Louis Barbier

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.


July 16, 2001: Mariner 9 arrived at Mars in 1971 -- the first spacecraft to orbit the Red Planet. Scientists were anxious to study the crisp new pictures it was expected to send back. Much of Mars had never been seen in any detail, and Mariner 9 would lift the veil at last.

Their feelings must have been mixed indeed when the first images arrived at mission control and revealed .... a world-wide haze. The surface of the entire planet was hidden by the biggest dust storm anyone had ever seen! Only Olympus Mons, a giant volcano 24 kilometers high, peeked above the clouds.

After a month the dust settled and Mariner 9 mapped the Red Planet with great success. Scientists have since learned that huge dust storms, dwarfing desert dust clouds on Earth, are fairly common on Mars. The Mariner 9 event still holds the record as the thickest and longest-lasting we have observed -- but perhaps not for long.

Above: On June 26, 2001, the Hubble Space Telescope spotted a dust storm brewing in Hellas Basin on Mars. A day later the storm "exploded" and became a global event.

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Three weeks ago a new dust storm erupted on Mars. It's the largest in 25 years and still growing. The storm is so big that amateur astronomers using modest telescopes can see it from Earth. And the cloud has raised the temperature of the frigid Martian atmosphere by a stunning 30 degrees Celsius. Now that's global warming!

Enjoying the best view of the storm is NASA's Mars Global Surveyor in orbit around the Red Planet. The spacecraft carries an instrument called "TES" -- short for Thermal Emission Spectrometer -- that can measure the temperature and dust content of the Martian atmosphere on a daily basis.

"This storm began as a small dust cloud inside the Hellas Basin, a 9-km deep impact crater in Mars's southern hemisphere," says Phil Christensen, the principal investigator for TES at Arizona State University. At first the cloud did little -- alternately growing and retreating as days passed, but never getting very large until June 27th. "That's when the storm exploded," says Christensen. "It crossed some critical threshold and really began to grow." By early July the dust cloud had spilled out of the Basin and wrapped itself around the entire planet.

I offer these different articles to remind us that nothing stays the same; not weather patterns, rotations of the planets and the moons, not our galaxy or universe. It is in a constant state of change and growth.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 8:49 am 
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What I would like to know with these speculations is, where is the energy going?

See, there's a problem with their idea that the atmosphere is somehow slowing things down - the atmosphere would have to be speeding up by massive amounts. It's the Law! Momentum is conserved. So if the planet is losing momentum, where is it going?

These people are speculating as if somehow the air can just slow things down and that's the only sign we will see but the planet is an incredibly massive object - slowing down by even a tiny amount is a ginormous amount of energy. Where is it? If we can see the change in speed, the atmosphere effects should be easily overwhelming our sensors yet they don't get a mention.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 1:41 pm 
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@ Acolyte:
I've read somewhere a while ago that tidal power plants were thought to be slowing down Earth's rotation to the speed of the orbiting moon, and at the same time they were increasing the speed of moon orbiting by generating waves in gravitation field.
As I hadn't heard of tidal power plants until then, I researched and found out that they (obviously) use the power of tidal waves.

Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy resource. Movement of tides causes a loss of mechanical energy in the Earth–Moon system: this is a result of pumping of water through natural restrictions around coastlines and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since its formation. During the last 620 million years the period of rotation of the earth (length of a day) has increased from 21.9 hours to 24 hours;[4] in this period the Earth has lost 17% of its rotational energy. While tidal power may take additional energy from the system, the effect is negligible and would only be noticed over millions of years.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 1:53 pm 
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That Earth-Moon exchange comes out to about 0.00000005 hours in 16 years. Or to put it another way, if the Venus discrepancy was to continue for 620 million years, the rate would be slower by 4,197,917 hours...

Given Venus has no moon, you may see why I am so puzzled. There seems to be a massive amount of energy gone missing. Transferring it to the atmosphere should produce VERY noticeable effects and they aren't getting a mention.

And given it is a closed system, I'm wondering how poor the basic math of modern scientists has become that they aren't screaming about the momentum loss.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 2:00 pm 
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Good point, I just realise that tidal power plants can explain the loss of energy on Earth but not Venus.
Will try to research about it.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 2:30 pm 
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the length of a day on Venus is about 2802 hours, so 6.5 minutes is about 0.00003867 times that, which doesn't sound like much, but when you factor in the mass of the planet, the difference in momentum is 2,357,974,294,690,210,000,000 kg m/s

And that is an amount of energy that I think will make all the tidal power we could take in the next 100 years look miniscule.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 2:41 pm 
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See Acolyte, I think you've just found the answer to our energy problem when crude oil runs out...now you just have to figure out how to get there! ;-)


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 3:09 pm 
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Venus and the earth are not spinning slower. It's just all our clocks (including the atomic ones) are running faster.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 3:32 pm 
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The academic helio-centric Copernican model of the Solar System is kaput
Image


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sat Feb 25, 2012 11:47 pm 
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Agartha wrote:
See Acolyte, I think you've just found the answer to our energy problem when crude oil runs out...now you just have to figure out how to get there! ;-)

OK... we don't have to go there. What we do is, at exactly the same moment, we get everyone on Earth to run East. 7 billion pairs of feet pushing the Earth against the spin will slow it down and we can tap all that energy and use it to power our world.

Then once a week we get people to do it again.

Not only do we get energy, but all the people in the west will have new houses once a week and we solve the population crisis as all the people living on eastern seaboards fall into the ocean and drown.

Has to be that way I'm afraid - if anyone goes back to the west they will undo the energy production.

Although... Hmmmm...

Maybe we could set it up so everyone runs East the first week, then runs back west the next week and we tap it both ways? We wouldn't get the same amount of population reduction but we'd get SOME benefit, and we wouldn't have to change our clocks - just have an Easter time one week where we set the clocks forward and a Wester time the next week where we set them back.

It'd help with the obesity problems as well, PLUS all those fat people would be producing MORE energy than the skinny ones so they could feel valuable in our society.

Win-win all the way around!

(Sorry for the level of humour; the Dead Horse thread got me in the mood and it's hard to break) :lol:


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sun Feb 26, 2012 12:26 am 
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vision-master wrote:
The academic helio-centric Copernican model of the Solar System is kaput
Image

LOLZ - or not. Just because someone posits an idea you don't understand does not make it truth. You tried this one on before and I replied with some problems but you never took them on board. That's why it is good to enter into rational conversations rather than taking random potshots from your lofty position of beliefs - you get to learn stuff and don't go repeating it and looking silly.

See... look at that model. Carefully. Go on, you can do it. It's obvious even in that picture...

Now tell me how it is that all the planets we see from Earth can disappear behind the Sun at regular and predictable intervals. The Sun is way out in front of all the planets, right? So how can ANY of the planets go behind it when viewed from another planet?

It sounds a nice idea but really it is just someone who doesn't understand that the Solar System is a whole, not lots of little pieces randomly being dragged along by the Sun. He seems to think the Sun somehow came upon the planets and scooped them up in its gravity field. It'd be an interesting exercise for him to work out just how each and every one of them somehow starts spiralling along behind the Sun instead of simply trailing it in a string.

That whole solar ecliptic thing is not a guess nor an idea, it is a measurable (and measured) fact of life. There IS a plane bisecting the Sun and all the planets revolve around the Sun very close to that plane. The most eccentric is Pluto, and it is only 17º off, AND it still averages to the ecilptic - in other words it goes above and below.

Pretty images do not, unfortunately, (or we could 'prove' anything we want to) stack up as proof of an idea - measurements and careful observations of reality are evidence that is difficult to refute.

Now, there IS an answer you could reply with that would open up a nice conversation but I'm betting you don't know it - it would require an understanding of what your guy is actually trying to say. So you have fun with that... :lol:


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sun Feb 26, 2012 12:49 am 
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Aco, you all can run; I will sit, watch and laugh
my calories off that way. What happens when the oceans interrupt the flow of runners?
I had found an article at work that indicated that some sciencetists thought that solar activity had something to do with the slowing of Venus' rotation. Not saying it is true; just saying what I read.


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 Post subject: Re: Venus Spinning Slower
PostPosted: Sun Feb 26, 2012 1:02 am 
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Summerland wrote:
Aco, you all can run; I will sit, watch and laugh
my calories off that way. What happens when the oceans interrupt the flow of runners?
I had found an article at work that indicated that some sciencetists thought that solar activity had something to do with the slowing of Venus' rotation. Not saying it is true; just saying what I read.

But it has to be ALL of us Summerland... (hm... you don't happen to live near an East Coast by any chance? :lol:

The Sun is a better possibility than the atmosphere - at least it is an outside source. The problem would be what it could be - Venus has bugger-all magnetosphere so any effect would almost have to be a physical one - what could it be that we haven't seen or felt?

I think eventually we will see more and more scientists begin to look for new theories. There are too many WTF? moments happening in fields where they say they've got it all but nailed down.

One thing I have never seen a comment on is electric fields. While Venus has no intrinsic magnetic field, it does have metals and moving metal through a magnetic field WILL induce current and an electric field. We know the Sun's magnetosphere reaches Earth so Venus is smack in it.

Also the solar wind is plasma, charged particles streaming out from the Sun - moving a charged planet through that HAS to generate the mother of all EMF fields.

So it is a possibility that the Sun could be influencing. But again the sheer scale of the energy transfer begs the question of what it could be. You'd think if it affected Venus so strongly we'd at least have had some effect here. Maybe Venus has an off-centre mass of metals that are causing a surge in the forces being applied as it spins? But then the attractive factor as the mass came around would balance the slowing factor as the mass moved away...

I admit, it's a puzzle. Just thinking out loud here BTW. One thing they should look at is possible measurement effects - we recently saw a spate of reports about the Sun altering radioactive processes - maybe their measuring devices are being affected?

There's some strange shit happening all around...


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