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taolung
2006-Aug-26, 07:24 AM
Hello all,

I'm debating a YEC (I hate myself...) and he tossed out some nonsense about how the sun is shrinking at such a rate that a few million years ago, it would have to have been so large that life on Earth couldn't have even survived.

Of course this assumes that the sun had to have been shrinking at a constant rate all that time. And I know that the information Creationists used to obtain this projection was quickly discredited - it's simply not accurate.

But it did get me to thinking - it makes sense that the sun is decreasing in mass as it's throwing out all the radiation, solar wind, etc. that it is. So my question is - how much mass is it actually loosing?

snarkophilus
2006-Aug-26, 07:41 AM
But it did get me to thinking - it makes sense that the sun is decreasing in mass as it's throwing out all the radiation, solar wind, etc. that it is. So my question is - how much mass is it actually loosing?

It's absorbing a bit of mass, too... after all, that's how it formed in the first place. A lot of what it ejects probably ends up inside it again.

I couldn't find any reliable sources in a quick initial search. I remember that Arnold Boothroyd at CITA published something about stellar evolution (I think in 2003), suggesting that the Sun was heavier in its young stages and predicting its future... you might see if you can find his web site and a link to something containing that information there.

Gillianren
2006-Aug-26, 07:57 AM
http://www.talkorigins.org/indexcc/CE/CE310.html--when in doubt, Talk Origins should have your answer.

cjl
2006-Aug-26, 08:29 AM
Gillian:

Did you mean to link to this (http://www.talkorigins.org/indexcc/CE/CE310.html)?

Ken G
2006-Aug-26, 08:43 AM
The Sun loses mass at so slow a rate that in the next billion years it will still lose only about a thousandth of one percent of its mass, due to the solar wind. The mass loss due to nuclear burning is about the same.

Jeff Root
2006-Aug-26, 09:16 AM
And -- surprisingly -- it is probably now extremely rare for the Sun
to gain mass. Anything that falls into it is completely vaporized
before reaching the photosphere. The resulting vapor is blown
away by the solar wind.

There must be some minimum size body which can partially hold
together all the way into the photosphere to become part of the
Sun, but I don't know what that size is. Probably on the order
of kilometers in diameter even for a stone or iron body.

-- Jeff, in Minneapolis

Gillianren
2006-Aug-26, 09:54 AM
Gillian:

Did you mean to link to this (http://www.talkorigins.org/indexcc/CE/CE310.html)?

Yes; apparently, the copy/paste didn't work. How odd.

Van Rijn
2006-Aug-26, 10:56 AM
It worked, you just included extraneous text within the URL tags.

Gillianren
2006-Aug-26, 07:07 PM
No, I didn't; I let the computer add the extraneous text all by itself. I don't bother with url tabs, since the board'll do 'em automatically. I have gone back and edited, though.

Tim Thompson
2006-Aug-26, 08:40 PM
Here's something I wrote on the topic a few years ago: A Response to the Shrinking Sun Argument (http://www.tim-thompson.com/resp8.html). It might use an update, but everything there is still correct. Since then there have been several more precise studies of the solar radius, and they are all in agreement with the same conclusion. The sun is not shrinking systematically in any observable manner.

In theory, over timescales of 10s or 100s of millions of years, the sun should contract slightly, in response to the decreasing efficiency of fusion in the core, as the hydrogen supply dwindles. But of course that will reverse itself dramatically when the sun swings into red giant mode, in 4 or 5 billion years.