If the Earth were at Venus' orbit, how much bigger would the tides be?

Leovinus · Apr 22, 2008

If the Earth were at Venus' orbit, how much bigger would the tides be?  Ignore the fact that at that range the oceans would boil away.  Just factor in the gravitational difference. <div class="Discussion_UserSignature"> </div>

Saiph · Apr 22, 2008

well, tidal forces act at the cube of the distance IIRC.  So venus is at about 3/4 of earth's seperation from the sun...So the solar tides are about 42% stronger.  But the lunar tides are, for earth, about twice as strong as solar tides.So if lunar tides are ~1m (in the open ocean, without coastal interference), solar tides on eart are at about 0.5m.  Boost them up to "Venusian" strength and you geet 0.71m solar tides, for a net tide of 1.71m on venus vs 1.5 m on earth.  Thats a net 14% gain. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Leovinus · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>well, tidal forces act at the cube of the distance IIRC.  So venus is at about 3/4 of earth's seperation from the sun...So the solar tides are about 42% stronger.  But the lunar tides are, for earth, about twice as strong as solar tides.So if lunar tides are ~1m (in the open ocean, without coastal interference), solar tides on eart are at about 0.5m.  Boost them up to "Venusian" strength and you geet 0.71m solar tides, for a net tide of 1.71m on venus vs 1.5 m on earth.  Thats a net 14% gain. Posted by Saiph</DIV>That's pretty interesting.  Thanks.  <div class="Discussion_UserSignature"> </div>

Saiph · Apr 22, 2008

Anytime leo

<div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Saiph · Apr 22, 2008

math error...and again I have the tiny post box!!! only one character wide.  Gofigure.  Here's hoping I don't make any typos. Anyway, I forgot a simple math manipulation.  The tidal force on earth is 0.41x the tidal force on venuse (dueto the sun).  That means the "Venus" solar tidal forces are  2.43x earths...they'd actually outstrip the lunar tides. at ~1.2m in ehight.  Making the tide total at 2.2m vs earths 1.5m.This is why I don't do math in my head. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Leovinus · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>math error...and again I have the tiny post box!!! only one character wide.  Gofigure.  Here's hoping I don't make any typos. Anyway, I forgot a simple math manipulation.  The tidal force on earth is 0.41x the tidal force on venuse (dueto the sun).  That means the "Venus" solar tidal forces are  2.43x earths...they'd actually outstrip the lunar tides. at ~1.2m in ehight.  Making the tide total at 2.2m vs earths 1.5m.This is why I don't do math in my head. Posted by Saiph</DIV>Even more impressive.  Probably at Mercury's orbit (again ignoring the heat factor) I bet I'd have oceans in my back yard here at mile-high Colorado!  <div class="Discussion_UserSignature"> </div>

bearack · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Even more impressive.  Probably at Mercury's orbit (again ignoring the heat factor) I bet I'd have oceans in my back yard here at mile-high Colorado!  Posted by Leovinus</DIV> Actually, I think the 2.2m or .07m increase would be marginal, but I'm wrong 98.7756% of the time.  <div class="Discussion_UserSignature"> <img id="06322a8d-f18d-4ab1-8ea7-150275a4cb53" src="http://sitelife.space.com/ver1.0/Content/images/store/6/14/06322a8d-f18d-4ab1-8ea7-150275a4cb53.Large.jpg" alt="blog post photo" /> </div>

Leovinus · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Actually, I think the 2.2m or .07m increase would be marginal, but I'm wrong 98.7756% of the time.  Posted by bearack</DIV>The correct figure is 98.7757% of the time.  You have to correct for the mistake in the 98.7756 figure.  <div class="Discussion_UserSignature"> </div>

Saiph · Apr 22, 2008

well, mercury is at 0.387 au, so cube it, and divide 1 by that answer gives...~17x the solar tide compared to earth, so 8.5m solar tides, plus ~1m lunar, for net mid ocean tides of ~10m. a little shy of a mile

<div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Leovinus · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>well, mercury is at 0.387 au, so cube it, and divide 1 by that answer gives...~17x the solar tide compared to earth, so 8.5m solar tides, plus ~1m lunar, for net mid ocean tides of ~10m. a little shy of a mile

Posted by Saiph</DIV> Sooo... if we have a 10-meter tide which is quite a lot -- would that mean that if we were standing on a scale at high tide it would read higher then if we weighed ourselves at low tide? <div class="Discussion_UserSignature"> </div>

bearack · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The correct figure is 98.7757% of the time.  You have to correct for the mistake in the 98.7756 figure.  Posted by Leovinus</DIV> Apparently my only contribution to these threads are my post count <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" /> <div class="Discussion_UserSignature"> <img id="06322a8d-f18d-4ab1-8ea7-150275a4cb53" src="http://sitelife.space.com/ver1.0/Content/images/store/6/14/06322a8d-f18d-4ab1-8ea7-150275a4cb53.Large.jpg" alt="blog post photo" /> </div>

Saiph · Apr 22, 2008

Well, your weight will vary due to how the sun's gravity and the planets gravity line up at those times...but I don't believe the tidal forces themselves affect your weight, as they create no net force (i.e. they won't cause you to move towards or away from source).At high tide the sun is either above, or below you (actually a bit off to the side, but no need for technicality here).  If it's above, it's gravity counteracts the planets just a bit, if it's below, it adds to it a bit.  If it's low tide, the sun is 90 degrees tot he side...and isn't adding or subtracting it's gravity at all (neutral). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Leovinus · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Well, your weight will vary due to how the sun's gravity and the planets gravity line up at those times...but I don't believe the tidal forces themselves affect your weight, as they create no net force (i.e. they won't cause you to move towards or away from source).At high tide the sun is either above, or below you (actually a bit off to the side, but no need for technicality here).  If it's above, it's gravity counteracts the planets just a bit, if it's below, it adds to it a bit.  If it's low tide, the sun is 90 degrees tot he side...and isn't adding or subtracting it's gravity at all (neutral). Posted by Saiph</DIV>My thought was that at high tide, the Sun would be trying to pull you off the planet, hence you would feel lighter.  The other way to look at it is that it is also taking you farther from the center of gravity because it is lifting the surface away from the planet core.  <div class="Discussion_UserSignature"> </div>

Saiph · Apr 22, 2008

Hmm...you've got a point there.  The tidal forces on your own body won't change your weight, that I'm sure of now, as tidal forces aren't a motive force.  The most they can do is torque about the center of mass.But, they do change distance between your feet, and the core of the planet.  So that miniscule shift in distance will create a difference in wieght.   But even at mercury's radius, it won't be noticable on any but the finest measuring devices.  A 20m difference between low and high tide vs the radius of a planet...isn't going to do much.  And that's on an ocean.  The tidal shifts of solid ground are a lot less than what I've quoted so far. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

l3p3r · Apr 23, 2008

nice saiph, I saw this question last night and didn't really know where to start hehe... thanks! <div class="Discussion_UserSignature"> </div>

Saiph · Apr 23, 2008

aside from asking about tidal forces which follow the 1/r^3 law, it's the same sort of question, and same sort of approach, as if Leo had asked "how much would I weigh on the moon? Or if the earth was twice as large?" But I'm glad to help.  <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

l3p3r · Apr 23, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Posted by Saiph</DIV> I also wonder if there might be major nonlinearities... like the thermal expansion of water in close proximity to the sun (though I guess we're discarding this) and also - are there nonlinear compressibility effects in the oceans? that is, if you reduce the local gravity on a patch of deep ocean by 10%, does the magnitude of the tide in that area rise in direct proportion? Or should it rise more in the last 5% compared with the first 5%? will the moon's gravity have more/less of an effect when compounded with the effects of increased proximity to the sun? <div class="Discussion_UserSignature"> </div>

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