Arrowman

On another thread I referred to a claim made by Helen Setterfield on the Baptist Board that, and I quote

As an aside here, George Dodwell, the late government astronomer for South Australia, did an enormous study near the end of his life on the earth’s axis tilt. His papers are in the process of being readied for publishing now. He was able to prove not only mathematically, but from ancient drawings, architecture and references as far back as possible that the earth did indeed change the tilt of its axis. This produced a wobble effect that not only ‘stopped’ the sun from going down at one point, but caused the shadow on the stairs in Hezekiah’s time to go backwards.

This smells to me like a mixture of fact (the tilt of the axis has changed in the past) and fiction (the tilt changed rapidly and recently - and as we shall see - as a result of an asteroid strike).

This is a new one to me and I'm interested in the opinions of those more knowledgeable on these things.

I've done a small amount of research - it seems that

- Dodwell researched ancient astronomical records and came to some conclusions about variations in the tilt of the earth's axis. I'm not sure just how innovative these discoveries were, or how much they align with conventional astronomy as opposed to von Daniken-like speculation.
- Barry Setterfield was (according to his own online material) asked by the local astronomical society to collate and publish Dodwell's papers.
- It appears that maybe Dodwell was a Bible-believing Christian, or reinforced his beliefs through his work.
- Barry Setterfield refers to Dodwell a number of times in his (Setterfield's) online publications; it is not clear how much Setterfield is quoting Dodwell's conclusions directly, and how much he is projecting/interpreting.
- It seems that Helen is saying not only that Dodwell did ground-breaking work (which he might have) on axis tilt, but that he found that - and here's the whacky part - an asteroid struck the earth during Biblical times, and caused the axis to tilt, thus (a) ending the ice age (within a YEC timeframe) and (b) causing strange things to happen to the apparent movement of the sun (as described in various places in the Bible.

Now, call me skeptical if you must - but: If an asteroid had struck the earth just a few thousand years ago, with sufficient mass/force to change the tilt of the earth's axis would we not see some evidence of this? Like, er, mass extinctions etc?

(Note I am not disputing the idea that an asteroid may have struck the earth at some stage in deep history - just that it's hardly plausible to propose that it happened just a few thousand years ago.)

I wait on education from the astronomers here present. I can post links for anyone interested.

excreationist

Well this is what I sent to the baptistboard for them to post:
=======================
EXCREATIONIST
Well according to Donald B. DeYoung's book, "Astronomy and the Bible", the
earth's tilt probably hasn't changed:
In Joshua 10:13 it says that the sun stood in the middle of the sky and
stopped going down for about a full day. It would have had to be a pretty
ordered wobble since it doesn't mention anything about the sun shaking from
north to south at all. The spinning of the earth around its own axis would
just be caused by momentum I think. If you're on the surface of the spinning
earth, I think the only way for it to appear that the earth has stopped
spinning is for it to stop spinning. Or you could be at the axis. So the
axis of rotation could have moved to where Joshua was. For the axis of
rotation to move I think there would need to be external forces that
"grabbed" the earth and shifted the axis of rotation.

In 2 Kings 20:9-11, the sun's movement reversed in the sky. Dr. DeYoung says
that the "ten steps" probably means that the time on the sundial went back
about 5 or 6 hours. In that case, the axis of rotation is still the same,
but the rotation is in the opposite direction. This would also need an
external force to happen I think.

But I guess God could have done it since he is all-powerful.

The problem is that as far as I know, no other cultures have recorded these
relatively recent amazing events. Perhaps those events never happened.
Surely the Egyptians would have noticed their sundials acting strangely and
decide to draw some hieroglyphics about it...

Quetzal

ex-C: What is it about Australians and asteroids? Another one of your countrymen, George Williams, proposed a glancing asteroid impact that changed the Earth's axial tilt. 'Course, he was using it as a mechanism for explaining how extreme obliquity was a cause of one of the Phanerozoic "snow-ball Earths", so he was talking 2.8 gya, not last Tuesday like the creationists. I don't think he got very far, because IIRC the proposed impact would have had fairly significant implications for little things like the Earth's orbital dynamics, to say nothing of the Moon's.

Just thought I'd add a non-sequitur 'cause the OP reminded me of it. Please continue.

RufusAtticus

I got five dollars that say that his papers will always be in production.

~~RvFvS~~

excreationist

Just about that...
That book's author, Dr. DeYoung, is part of the AiG crew and is a professor and he teaches physics and astronomy...
Anyway, he said:
"...would have left permanent evidence, and that is not present today. For example, an elliptical moon orbit would be expected to result from lunar gravity interaction with a colliding object. However, the moon's orbit deviates a mere 12 percent from a perfect circle."

But as I said earlier, a changing tilt doesn't really explain those Bible verses anyway...

Camaban

is that "Paul DeYonghe"?

(He's an Administrator/Moderator, one or the other on another board I'm on. Although it's been a while since he touched the creationist forum)

excreationist

No, he's called <a href="http://www.answersingenesis.org/home/area/bios/d_deyoung.asp" target="_blank">Donald DeYoung</a>.

Here's a pic of the book:

KeithHarwood

It depends on what you mean by mass extinction. If you mean the relatively trivial thump of 65Mya or the rather more substantial Permian mass extinction then, no, you wouldn't expect to see that. On the other hand, if you mean all life extinguished and the entire surface of the planet molten, then yes, you would expect it. Indeed, there is some evidence that Venus was resurfaced that way about 800Mya.

Do the maths. Pick a decent sized object coming in at some appropriate angle at at least 11Km/s (it can't come any slower), apply conservation of angular momentum to get the new axis of rotation. Now apply conservation of energy of the system to get the total heat produced, then divide by the heat capacity of the top, say, kilometre of the surface of the earth to get the final temperature.

BTW, the earth's axis does wander as earthquakes and similar occurances change the moment of inertia of the planet, but the changes are small. They used to be documented in the Explanatory Suppliment to the Astronomical Ephemeris. (Probably still are, but I'm out of touch these days.)

Seth K

This sure sounds like a barely modified rehash of the "NASA computers found Joshua's missing day" myth. (Which was itself a modified rehash of a late 19th century story, re-told in the 1930's, etc.) As evidence of a re-worked urban legend, I note that the NASA story and its forebearer both include Hezekiah's stairs as well. See <a href="http://www.snopes2.com/religion/lostday.htm" target="_blank">www.snopes2.com</a> for details.

[edited URL--sk]

[ June 16, 2002: Message edited by: Seth K ]</p>

Jesus Tap-Dancin' Christ

A "mere" twelve percent? In math land, a circle that is 12% of is called...elliptical. 0% off is circular. Oooooops. Not that I take the other wacko's side.