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Author Topic: Is the Earth more massive in the summer?  (Read 2366 times)

Offline Lamprey5

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Is the Earth more massive in the summer?
« on: 01/05/2011 22:19:13 »
According to Kepler's Laws, the Earth is at its greatest velocity when it is closest to the Sun, when it is also hottest. It also has a greater gravitational potential energy with respect to the Sun.
The Earth therefore has greater kinetic, gravitational, and thermal energy in the summer than in the winter, spring and fall. Does this mean the Earth is more massive in the summer?
This would also result in the Earth having gravitational field strength.. correct?
Does the commonly used 9.807 N/kg field strength of the Earth take into consideration the increased field strength during the summer from its increased mass?


 

Offline Bored chemist

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Is the Earth more massive in the summer?
« Reply #1 on: 02/05/2011 10:35:32 »
Who's Summer?
The North's or the South's?
Anyway, any change would be far too small to measure.
 

Offline Phractality

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Is the Earth more massive in the summer?
« Reply #2 on: 02/05/2011 17:49:23 »
Earth is closest to the Sun in December; that is called perihelion. That's northern winter and southern summer. At periphelion, a planet has more kinetic energy and less potential energy, but the total energy of any orbiting body is constant.
 

Offline Lamprey5

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Is the Earth more massive in the summer?
« Reply #3 on: 04/05/2011 01:36:57 »
But what about the inrease in thermal energy of the earth because it is closer to the sun? There is a greater radiative flux at perihelion; is there not? And hotter objects are more massive than the same object at a lower temperature. Wouldn't the collective increase in thermal energy of the earth change it's mass by a measurable amount?
 

Offline yor_on

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Is the Earth more massive in the summer?
« Reply #4 on: 04/05/2011 02:40:54 »
The closer you get to another heavenly body the greater the tension created inside, that's why our moon has stopped its spin, to show us only one 'face' looking down at us. The tension created will radiate out energy as the material tense and relax (kinetic energy as Phractality state). And that means that you lose energy, as I understands it, by interacting gravitationally with the sun.

As for heat being transfered into mass you're correct though. But that's a transient process like heating a iron. Whereas the energy you lose by a heavenly body's mass interacting with itself should be a true loss of energy, as I see it?
 

Offline Phractality

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Is the Earth more massive in the summer?
« Reply #5 on: 04/05/2011 03:04:23 »
Wouldn't the collective increase in thermal energy of the earth change it's mass by a measurable amount?
The motion of molecules due to heat is a tiny fraction of the speed of light, and the mass increase is proportional to the square of the speed. To get a measurable increase in mass, you would have to heat the whole Earth all the way to the core until it is many times hotter than the sun.
 

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Is the Earth more massive in the summer?
« Reply #5 on: 04/05/2011 03:04:23 »

 

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