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"the beauty of the sky is even better when you have no idea what you are looking at."

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"the beauty of the sky is even better when you have no idea what you are looking at."

Welcome to the board, AstroTodd!

Welcome to the board, AstroTodd!

[You can delete your duplicate post. There has been some noticeable delay time in accepting posts, for some reason. This should, hoepfully, be fixed soon.]

Once one has been recognized as answering the previous question, then this person will ask one. So, you may not ask your interesting question at this time.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

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"the beauty of the sky is even better when you have no idea what you are looking at."

You're in the right area, George!

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- There must be a new moon out, she said. He's always bad then.

Apologies for being away. My ISP decided to accidentally disconnect me for a couple of weeks. It didnt matter though as Eroica was entirely correct - for his info, the H5 is on display in Guildford, oh and the scilly isles started the whole longitude prize thing by wrecking the English fleet in 1714 (told you it was a bit silly)

Ah ha! [Bludgeoning has its rewards. ]

Perhaps he used the fresh surface magma temperature (~ 1300 C max.) for his equations and did not consider that it could be much hotter. [Core temp. is estimated to be 5000 C]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

he was using the wrong temperature scale.

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I've met ngc3314


"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
My travel blog

Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

Ooooh, nice air ball!! [basketball term]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Getting colder again. Think about the thermodynamic mechanisms by which heat might be lost by the Earth...

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- There must be a new moon out, she said. He's always bad then.

If you would call me Lord George, I might be able to think more like him.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Eroica,

Are you on slightly dodgy ground with this one? Thomsonś calculations failed for two reasons - 1- he didnt know about radioactivity and 2- he also didnt know about convection within the molten core. The radioactivity bit explains about 60% of the problem and is the principal fault and was the reason that Thomson conceded defeat in 1905.

However I think youŕe getting at the fact that Thomson based his calculations on conduction (Fourier theory) and radiative cooling, neglecting the possibility that the interior of the earth would be molten and therefore convective.

maybe he didn't know anything about black body radiation.

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I've met ngc3314


"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
My travel blog

Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

I just did a google on "Kelvin sun earth" and it came up with a couple pages of interest. This wiki page mentions Kelvin's calculations for the sun and points to this page which says "Unfortunately the resulting age estimate was only 20 million years, well short of the time span of several billion years suggested by geology."

One of Kelvin's lectures, from 1887, is online, and it was interesting reading. " It is worth commenting that Thomson is, of course, entirely wrong but there was no way before the discovery of the structure of the atom that he could possibly have produced a correct theory. The lecture is interesting both in showing the knowledge of the period, and also in showing how the leading scientists pushed forward the bounds of knowledge. "

Correct!

Source: Kate Bradshaw et al. (1998), S103, Discovering Science, Block 10, Earth and life through time, The Open University, Milton Keynes.

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- There must be a new moon out, she said. He's always bad then.

Kelvin might have conceded defeat for this reason, but he was wrong to do so. It was not until long after 1905 that we learnt enough about how much radiogenic material is in the Earth's interior and how it is distributed to arrive at an accurate assessment. The 1905 estimates of these things were inaccurate and much too high (hence your 60% figure).

In fact, it was not until the advent of plate tectonics in the second half of the 20th century that the discrepancy was finally resolved.

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- There must be a new moon out, she said. He's always bad then.

The way I read that passage, and from what I've learned elsewhere, I would have to say that ozark1 is correct that the principal fault is not addressing the radiogenic heating.

Does Kate Bradshaw et al. go on in the text about "it is a commonly repeated myth that Kelvin's big mistake was to ignore the radioactive decay of uranium"? What do they say?

The passage I quoted from is entitled The real reason why Kelvin got the age of the Earth wrong.

It begins:

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- There must be a new moon out, she said. He's always bad then.

As ozark1 says, it is much less significant. I guess the question is how much?

Do they have a reference?

PS: I just googled "kate bradshaw"+"discovering science" and nothing came up. Is there another title I should use?

PSS: Here's another reference that appears to say something similar, but has only the abstract.

PSSS: Ah, that references Kelvin's assistant Perry. Here's another column that says essentially what you're saying, that it is convection that is the issue. However, it points out that Perry's model has an interior core that goes to within 30 miles of the interior, and it is well-stirred. That quite a bit away from the current understanding too. The column he is correcting.

PSSSS: Don Anderson article on the Energetics of the Earth. Weirdly, he seems to be saying that convection doesn't pipe a lot of the heat to the surface, from the core.

Anyway, good question Eroica. I assume ozark1 is next?