'Rising tide'

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18 Jun 2009, 3:43 pm

There would still be tides, but they would be from the sun, and very weak, also the planet would be very different possibly similar to Venus, only not as hot.

willa
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18 Jun 2009, 4:09 pm

lau wrote:

I'd quite like a pointer to somewhere that tells about this "the moon makes us wobble LESS" idea.

With the three body case (Sol/Earth/Moon), we have quite rapid (astronomically speaking) chaotic changes of orbits, etc.

In a simpler two body case (Sol/Jupiter), there is little chaotic going on - they essentially just follow elliptic orbits about their centre of mass.

First thing that came up on google was a link to this video. 'Bout 2 mins in. Very nicely explained (go to about 2 mins in). Looks like its a middle section of an hour long show, will have to watch it all.

http://www.youtube.com/watch?v=QNOY4szn ... 61&index=2

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Michjo
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18 Jun 2009, 4:20 pm

Quote:

Water is essential to our kind of life. We are 70 percent water. Without water the kind of life we have on earth, base on RNA and DNA would not exist.

Context. I never claimed otherwise. Lau suggested that scientists beleive life not human life, is dependant upon water. I was disagreeing, scientists have proposed many different systems of life.

As for some differences... the moon slows the speed at which the earth spins at. If there was no moon, a day would be around 6 - 8 hours. There would be dramatic weather differences, more storms, extremely fast winds.

The same tidal interactions are actually pushing the moon away from the earth, and the further away the moon gets from the earth the longer the day becomes.

Tidal interactions also help heat the earth up, although wether that would create a noticable difference i have no idea.

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18 Jun 2009, 5:18 pm

I've never heard the wobble nonsense, but its pretty well known lau, that the moon causes tides.

And its well known that tide pool life was germinal in the development of both land based vertebrates and non aquatic plant life.

So yes, no moon = no life as we know it.

Rebuttal?

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18 Jun 2009, 5:22 pm

lau wrote:

See http://www.nature.com/nature/journal/v3 ... 615a0.html

also

from http://astrobio.net/index.php?option=co ... il&id=2507

The Moon has been a stabilizing factor for the axis of rotation of the Earth. If you look at Mars, for instance, that planet has wobbled quite dramatically on its axis over time due to the gravitational influence of all the other planets in the solar system. Because of this obliquity change, the ice that is now at the poles on Mars would sometimes drift to the equator. But the Earth’s moon has helped stabilize our planet so that its axis of rotation stays in the same direction. For this reason, we had much less climatic change than if the Earth had been alone. And this has changed the way life evolved on Earth, allowing for the emergence of more complex multi-cellular organisms compared to a planet where drastic climatic change would allow only small, robust organisms to survive.

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18 Jun 2009, 7:16 pm

ruveyn wrote:

lau wrote:

I'd quite like a pointer to somewhere that tells about this "the moon makes us wobble LESS" idea.
...

See http://www.nature.com/nature/journal/v3 ... 615a0.html

also

from http://astrobio.net/index.php?option=co ... il&id=2507

...

Interesting links. There does seem to be some doubt, when I find a reference to True polar wander, which seems to suggest that all is not quite as stable as suggested.

I see no explanation given for the stability. Do I presume it is due to the non-spherical shape of the Earth?

Then again, you do get these strange near-stable orbital dynamics, such as the behaviour of Cruithne.

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ruveyn
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19 Jun 2009, 8:34 am

lau wrote:

ruveyn wrote:

lau wrote:

I'd quite like a pointer to somewhere that tells about this "the moon makes us wobble LESS" idea.
...

See http://www.nature.com/nature/journal/v3 ... 615a0.html

also

from http://astrobio.net/index.php?option=co ... il&id=2507

...

That stabilization follows from the conservation of angular momentum. If you want the full bore treatment read an advanced treatise in celestial mechanics. You will have to face the math bravely.

ruveyn

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19 Jun 2009, 9:05 am

ruveyn wrote:

...
That stabilization follows from the conservation of angular momentum. If you want the full bore treatment read an advanced treatise in celestial mechanics. You will have to face the math bravely.

ruveyn

The maths is not a problem. Some time ago (in the seventies?) I wrote a program to calculate ephemeris data. Lunar orbital simulation is a mess. I researched it throughout a mass of libraries in London (the special collection in Waterloo, the patents office (nice stuff), UCL, etc). It was very hard to come up with anything that gave tolerable results for more that a few years. The initial "approximations" couldn't even get through a single year, with any degree of accuracy.

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19 Jun 2009, 9:47 am

ruveyn wrote:

lau wrote:

So the chaotic wobbling would of occurred due to the gravitational influence of other bodies? I'll check the links for interest sake.

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