21 Aug 08
Originally posted by Shallow BluePumice has an average porosity of 90%, and is only initially floating on water.
Are you sure? Have you weighed them against a duck?
Richard
Ordinary rock, granite, taken as an example, has an average density of 2.75 kg/dm3 (not the 5 kg/dm3 as I stated earlier).
Duck? Is this a reference to the Flintstone family? 🙂 No, even a rockduck can float.
23 Aug 08
1 edit
Originally posted by OmnicronYou mean, by the surface tension? Oh, yes, but I don't consider talc as a rock.
Depends on the type of "rock" and size. If the "rock" is small enough it may float due to hydrophobicity, for e.g. talc or gypsum and graphite (is graohite a rock?).
Saturn is not a piece of rock, it, as a whole, has a density less that of water.
24 Aug 08
Originally posted by FabianFnasI have always wondered how Jupiter has counter current gas flow?
You mean, by the surface tension? Oh, yes, but I don't consider talc as a rock.
Saturn is not a piece of rock, it, as a whole, has a density less that of water.
And it is so consistent, seems like it would be more erratic, like earth's atmosphere.
There is an excellent time lapse taken from space on Wikipedia:
http://en.wikipedia.org/wiki/Jupiter
24 Aug 08
Originally posted by mlpriorMy first guess is that the particles that make up those bands were captured from space (or maybe spit up from below) with a component of their velocity tangent to a sphere centered on the planet (for example, the surface, if Jupiter has one). Thus the fat white middle band, moving to the right, came in from one direction and gravity curved it's motion into a circle, while the skinny white one below the bubble, below the fat white band, moving to the left, was flying through space at a different angle and was caught by gravity going the other way.
I have always wondered how Jupiter has counter current gas flow?
And it is so consistent, seems like it would be more erratic, like earth's atmosphere.
There is an excellent time lapse taken from space on Wikipedia:
http://en.wikipedia.org/wiki/Jupiter
24 Aug 08
1 edit
Originally posted by FabianFnas
Pumice has an average porosity of 90%, and is only initially floating on water.
Ordinary rock, granite, taken as an example, has an average density of 2.75 kg/dm3 (not the 5 kg/dm3 as I stated earlier).
Duck? Is this a reference to the Flintstone family? 🙂 No, even a rockduck can float.
Wow. I should show that to the science class I'm going to be teaching.
24 Aug 08
Originally posted by AThousandYoungI suppose that is possible, though I would think the different bands would eventually slow each other down due to friction.
My first guess is that the particles that make up those bands were captured from space (or maybe spit up from below) with a component of their velocity tangent to a sphere centered on the planet (for example, the surface, if Jupiter has one). Thus the fat white middle band, moving to the right, came in from one direction and gravity curved it's motio ...[text shortened]... t, was flying through space at a different angle and was caught by gravity going the other way.
It seems like something is keeping them going. Possibly due to pressure gradients on the surface?
26 Aug 08
Originally posted by mlpriorIf they slowed down they'd drop into the surface of the planet. Orbit required a certain angular velocity.
I suppose that is possible, though I would think the different bands would eventually slow each other down due to friction.
It seems like something is keeping them going. Possibly due to pressure gradients on the surface?
26 Aug 08
1 edit
Originally posted by AThousandYoungI get the part about centripetal force but don't see the part about a non-spinning planet having a thinner atmosphere at the equator. Maybe he means it would be thinner compared to a spinning planet but not thinner than the polar regions of a non-spinner. It seems to me without spin there would be very little dif between poles and equator, at least at the same altitude.
Gravity acts as centripetal force best when the center of the Earth is also close to the center of the circle of orbit. Air particles are basically orbitting the Earth when it and they spin.
If an air particle were going around, say, one of the higher latitutes, gravity would have two compents; a centripetal one, and one that pulls the air particle toward the equator. Think about it.
There might be regional differences due to mascons under the surface with more pressure at places of higher than average gravitational attraction due to high density blobs under the surface (mascons) and places of slightly less pressure where the underlying structure has less density.