[elijah77jc]

Originally Posted by Lightknight

Perhaps you should be a bit more explanatory to her. I feel like her question was not directly answered.

while i admit that my avatar is a bit misleading, please don't tell me that you think i'm a girl.

come on gavin, we've crossed lines in the past.

[jdironfist]

Originally Posted by elijah77jc

while i admit that my avatar is a bit misleading, please don't tell me that you think i'm a girl.

come on gavin, we've crossed lines in the past.

Plus, Elijah's a guy .

Love in Him,
Joel

[jdironfist]

Originally Posted by JerryLove

As to the question of the loss of mass, the rate is hard tobe certain on. We can estimate the mass lost through the fusion of hydrogen into helium by looking at the sun's energy output; but I don't think we have an accurat model of nutrino loss, nor are we certain how much mass the sun gains from consuming matter around it.

I thought we actually did have a decent model of neutrino loss. It would go something like this:

The Sun operates on the proton-proton cycle (it fuses hydrogen into helium). So for every hydrogen involved in the fusion, you add a proton (I think it's safe to ignore the electrons because this deep into the Sun, the electrons have been stripped off the atom due to the immense pressure). Now, this is a problem—helium not only has two protons, but also has two neutrons. In the proton-proton cycle, four hydrogens are actually consumed, but two of the protons become neutrons. This transformation causes two neutrinos to be emitted, one for each proton that is turned into a neutron. So the equation would look something like this:

4H⁺ ==> 1He₄ + 2 neutrinos (normally denoted with the Greek letter "nu")

Using this equation, the mass of a proton, and the mass of a helium-4 atom, we can (I think) figure out how much mass is lost, given the number of fusions that happen per day (which I think can be calculated, but I can't remember).

Originally Posted by JerryLove

It's not as simple as you believe it to be. The orbit of the Earth varies over time. Sometimes more circular, sometimes more elliptica, sometimes farther out, sometimes farther in. In addition to the inherent issues with any orbiting body, the effects of other gravitic sources (other planets for example) cause both cyclial and non-cyclical changes in orbit.

The Earth's axis rotates in 41,000 year cycles, the obliquity cycles in 1,250,000 year cycles, orbital eccentricity every 100,000 years or so. Then there are the several cycles in solar activity to deal with.

Reality is far more complicated than you give it credti for.

In other words, we can't assume the cow is a sphere ? Bummer.

Love in Him,
Joel

[JerryLove]

I thought we actually did have a decent model of neutrino loss. It would go something like this:

I think the issue has been in verifying that number; though it may indeed be accurate. Nutrions have that annoying tendancy to pass through detectors.

In other words, we can't assume the cow is a sphere ? Bummer.

Well it would make the math easier

[nate95366]

Generally speaking, the volume of the Sun is more directly a function of its internal (core) temperature than its mass. The heat energy radiating from the core provides a force counter-active to gravity. Now, mass does play a part in how hot the core of the sun gets, but so does the availability of fusible materials (hydrogen and helium in the sun's case). If the core of the Sun were hotter (as seen in other stars principally fusing helium), the Sun would be larger (greater volume) and its surface would be cooler (i.e. a red giant of sorts). If the Sun's core were cooler, the sun would be smaller, and its surface may actually be hotter (i.e. a white dwarf of sorts). The former situation is more common than the latter, unless you speak of stars that have basically stopped doing fusion and are just cooling off slowly (which would be most white dwarves).

At least that's how I understand it?...

Nate

[himself12]

The sun is "burning" and therefore becoming smaller in mass.
Therefore, the gravitation must also become smaller over time.
That will have influence on the gravitation force that holds the planets in orbit around the sun.
1 bill. years ago the gravitation force of the sun would have been must greater, which again would have influence on the orbits of the planets.

Mercury is the closest planet. There must be a limit to how large the mass / gravitation force from the sun could be before Mercury would had been pulled in to the sun.

[JerryLove]

Originally Posted by himself12

The sun is "burning" and therefore becoming smaller in mass.
Therefore, the gravitation must also become smaller over time.

Yes. Loss of mass as the result of both conversion to energy and expulsion of particles.

The mass converted to energy over the entire life of the Sun to date is about 3.1 x 10^29 grams. The mass of the Sun is 4 x 10^33 grams so this loss equals 0.008 percent of its current mass.

The Sun also produces a 'solar wind' of particles at a rate of about 10^-14 solar masses per year. In 4 billion years this amounts to about 0.001 percent of the Sun's mass

That will have influence on the gravitation force that holds the planets in orbit around the sun.

Yes. Their orbits are generally getting larger.

1 bill. years ago the gravitation force of the sun would have been must greater, which again would have influence on the orbits of the planets.

The gravity was about 0.002% higher.

Mercury is the closest planet. There must be a limit to how large the mass / gravitation force from the sun could be before Mercury would had been pulled in to the sun.

Yes.