Maybe you sci.astro.amateur and sci.astro readers can explain this

"Common Man" wrote in message
news.com...
Note to the readers of sci.astro.amateur and sci.astro:

Pearl is a regular in the alt.animals.ethics.vegetarian newsgroup and
claims that the earth could be hollow. She goes on to claim that this
could have been caused by a rapidly spinning early earth. I've tried
to explain (without success) that such a rapidly spinning body would
flatten out rather than become hollow.

If any of you wish to take a crack at explaining this to her, feel
free.

For Pearl: Evidence that a rapidly spinning object would flatten out,
not become hollow.

See: http://www.govertschilling.nl/artike.../030612_sc.htm

Hmmm, we might be orbiting a tad differently if our mass were significantly
different than we have guessed it to be as a semi-solid core. Talk about
global warming.

Tom

Tom Hole wrote:
Hmmm, we might be orbiting a tad differently if our mass were significantly
different than we have guessed it to be as a semi-solid core. Talk about
global warming.

Heh.

But the mass is known from Newton's laws (from the Moon's distance and
orbital period), not from estimates based on the Earth's composition.
That composition is understood from observations of wave propagation
through the Earth's innards, and you're quite right that if the Earth
were hollowed out in any way (including like a donut), those waves would
propagate quite differently than they do in fact.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Tom Hole wrote:
Hmmm, we might be orbiting a tad differently if our mass were significantly
different than we have guessed it to be as a semi-solid core. Talk about
global warming.

Heh.

But the mass is known from Newton's laws (from the Moon's distance and
orbital period), not from estimates based on the Earth's composition.
That composition is understood from observations of wave propagation
through the Earth's innards, and you're quite right that if the Earth
were hollowed out in any way (including like a donut), those waves would
propagate quite differently than they do in fact.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt