Sad beyond words: which of the four orbits Earth?
Desertphile
1) Moon
2) Sun
3) Mars
4) Venus
According to the French version of "Who Wants to be a Millionaire?" the
answer is "Sacred blue! Fuckall if I know!" And France has The
Bomb......
Lee Jay
> Which of the four objects listed below orbits Earth?
>
> 1) Moon
> 2) Sun
> 3) Mars
> 4) Venus
I'll take none of the above, Bob.
The Earth and Moon each orbit their collective center of gravity, as do
the Earth and Sun.
Of course, even that isn't true if you want to get into multi-body
mechanics (which is a good way to get a headache).
It really is pathetic how little the general public knows of even very
basic science.
Lee Jay
Martin Andersen
the Earth on average.
Martin
I'd give the 'correct' answer. "What's your frame of reference?"
That'll stitch 'em up :)
Lee Jay
> Yet, the barycenter of the earth/moon orbit is about 1707km below the surface of
> the Earth on average.
Yep. And that's not at Earth's center. The CG of the whole solar
system is inside the Sun, isn't it?
Lee Jay
dkomo
Heh. I'll take all of the above. It depends on what you use as a
reference point. If you stand st the center of gravity, then the earth
and moon both orbit around you. But...
If you stand on the moon, the earth appears to orbit the moon. And...
If you stand on the earth, the moon, sun, mars and venus, as well as all
the stars in the heavens appear to orbit the earth, as the ancient
astronomers discovered.
It's all relative, as Einstein said. There is no absolute reference
point in spacetime.
Kevin Wayne Williams
Yep. When a million bucks is on the line, the best thing to do is to be
a smartass.
Natural selection works in strange and mysterious ways. I bet that after
a stunt like that, you wouldn't be getting any for a long time.
KWW
Free Lunch
Martin <use...@etiqa.co.uk> wrote in
<459f004b$0$27099$db0f...@news.zen.co.uk>:
Boston, of course. It's the hub of the universe.
Lee Jay
> Lee Jay wrote:
> > I'll take none of the above, Bob.
>
The difference between us getting the wrong answer and they guy that
actually got the wrong answer, is we can defend our choices. That, and
that we're getting the wrong answer on purpose! ;-)
Lee Jay
Lee Jay
> Yet, the barycenter of the earth/moon orbit is about 1707km below the surface of
> the Earth on average.
It just occured to me that you could make this question a lot harder by
asking it more correctly. Something like:
"Earth plus which of the following objects has its barycenter inside
the Earth?"
Or something to that effect.
Lee Jay
Desertphile
Thank you one and all for the replies. Amazing what one learns in
talk.origins.
The answer "Luna" was the most correct, of course, but not exactly
correct for tedious spoil-sport scientists who would rather be correct
than be a millionaire. http://www.earthmatrix.com/moon/barycenter.html
"The Earth's moon does not actually orbit around the Earth, but around
the Earth-Moon barycenter. And, likewise, the Earth also orbits around
this point. The Earth revolves around the barycenter 1/month." There is
a good diagram on the web page.
John Wilkins
And so do the Americans, and they think evolution doesn't happen...
--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: scienceblogs.com/evolvingthoughts
"He used... sarcasm. He knew all the tricks, dramatic irony, metaphor,
bathos, puns, parody, litotes and... satire. He was vicious."
R. Baldwin
news:n62up2tog3hbf8ddr...@4ax.com...
No. Fremont, in Seattle, is the center of the Universe.
John Wilkins
But the hub is where the wheels are...
Timberwoof
"Lee Jay" <ljfi...@msn.com> wrote:
Yes, but not in the Sun's center either.
--
Timberwoof <me at timberwoof dot com> http://www.timberwoof.com
It's easy to say a war is so important your neighbor should go fight it for you.
Elf M. Sternberg
> Desertphile wrote:
>> Which of the four objects listed below orbits Earth?
>>
>> 1) Moon
>> 2) Sun
>> 3) Mars
>> 4) Venus
>
> I'll take none of the above, Bob.
>
> The Earth and Moon each orbit their collective center of gravity, as do
> the Earth and Sun.
Yeah, but given that the collective center of gravity for the
Earth-Moon system is located within the lithosphere of the Earth, it's
probably a safe bet to say that the Moon orbits the Earth. (Trust me,
I've tried having this argument with my wife, and she, being a
geologist, takes the view I espoused. I voted for your explanation.)
Elf
R. Baldwin
news:1hriumt.18dq5y9bkbop5N%j.wil...@uq.edu.au...
> R. Baldwin <res0...@nozirevBACKWARDS.net> wrote:
>
>> "Free Lunch" <lu...@nofreelunch.us> wrote in message
>> news:n62up2tog3hbf8ddr...@4ax.com...
>> > On Sat, 06 Jan 2007 01:49:04 +0000, in talk.origins
>> > Martin <use...@etiqa.co.uk> wrote in
>> > <459f004b$0$27099$db0f...@news.zen.co.uk>:
>> >>Desertphile wrote:
>> >>> Which of the four objects listed below orbits Earth?
>> >>>
>> >>> 1) Moon
>> >>> 2) Sun
>> >>> 3) Mars
>> >>> 4) Venus
>> >>>
>> >>> http://tinyurl.com/yhjyew
>> >>>
>> >>> According to the French version of "Who Wants to be a Millionaire?"
>> >>> the
>> >>> answer is "Sacred blue! Fuckall if I know!" And France has The
>> >>> Bomb......
>> >>>
>> >>rofl
>> >>
>> >>I'd give the 'correct' answer. "What's your frame of reference?"
>> >
>> > Boston, of course. It's the hub of the universe.
>> >
>>
>> No. Fremont, in Seattle, is the center of the Universe.
>
> But the hub is where the wheels are...
What's this hub, bub?
Lee Jay
> In article <1168048531.4...@s80g2000cwa.googlegroups.com>,
> "Lee Jay" <ljfi...@msn.com> wrote:
> > Yep. And that's not at Earth's center. The CG of the whole solar
> > system is inside the Sun, isn't it?
>
> Yes, but not in the Sun's center either.
It must get close at times, with planets on all sides.
Lee Jay
Shane
It most likely always faces Jupiter, which is the, overwhlmingly, next
largest single mass in the solar system
Lee Jay
Yeah, but it's not the farthest away. What if Saturn and Neptune were
on the other side?
Lee Jay
Lee Jay
http://www.astronomycafe.net/qadir/q2927.html
Lee Jay
George
"Timberwoof" <timberw...@infernosoft.com> wrote in message
news:timberwoof.spam-51...@nnrp-virt.nntp.sonic.net...
Umm, after re-reading the OP question, I don't see where it was qualified
that any of those bodys had to orbit from the center of the earth.
George
John Wilkins
Sorry, I'm tyred of all this. I made an axle-dent, leave it at that.
Josh Hayes
news:1168051786.2...@11g2000cwr.googlegroups.com:
Well, geez, this is practically jesuitical.
In fact, NOTHING orbits anything else, really, does it, so long as it
has non-zero mass (and if it has zero mass, there's no gravitational
attraction so it doesn't orbit anything anyway).
But it's convenient approximate shorthand to say that "Earth orbits the
Sun", or "Luna orbits Earth". It's sure a hell of a lot more correct to
say the moon orbits Earth than that, say, Mars orbits Earth.
(Does anyone remember the first episode of "Lost In Space", where the
ship blasted off, passed the orbit of Saturn or something, and mission
control solemnly declared it had "left our galaxy"? Jeepers!)
-JAH
Why yes, I am rather older than some people here.
John Wilkins
Damn, yes! But that was in the first unfunny season, before they
realised it would make a better comedy.
>
> -JAH
>
> Why yes, I am rather older than some people here.
Not all, junior...
Radix2
Oh Christ. Who let Wilkins out?
Back in your box John!. You are beyond bearing.
George
"Josh Hayes" <jos...@spamblarg.net> wrote in message
news:Xns98AFE6EE9EC...@216.168.3.44...
Whatever it does, "it still moves".
George
Geoff
news:1168044806.0...@11g2000cwr.googlegroups.com...
> Which of the four objects listed below orbits Earth?
>
> 1) Moon
> 2) Sun
> 3) Mars
> 4) Venus
>
> http://tinyurl.com/yhjyew
>
> According to the French version of "Who Wants to be a Millionaire?" the
> answer is "Sacred blue! Fuckall if I know!" And France has The
> Bomb......
I swear he says, "Merde" when they reveal the answer.
Umberto Ramirez
"Geoff" <ge...@nospam.com> wrote:
And that wasn't even one of the choices!
(but yeah, I think he did say that - maybe they didn't know it was a
swear word)
Desertphile
John Wilkins wrote:
> Desertphile <deser...@hotmail.com> wrote:
>
> > Which of the four objects listed below orbits Earth?
> >
> > 1) Moon
> > 2) Sun
> > 3) Mars
> > 4) Venus
> >
> > http://tinyurl.com/yhjyew
> >
> > According to the French version of "Who Wants to be a Millionaire?" the
> > answer is "Sacred blue! Fuckall if I know!" And France has The
> > Bomb......
> And so do the Americans, and they think evolution doesn't happen...
Agreed entirely. It's a goddamned sorry state of affairs given the
existance of the internet. I suspect citizens of France is better
educated and better informed than citizens of the USA.
Desertphile
I just read about a poor sour from Germany who wanted to go to Sidney
Australia and ended up in Sidney Montana. He spent three days in the
airport waiting for family and friends to send more money to him so he
could go back around the other side of the planet.
dkomo
I simply happen to think Ptolmaic astronomy was pretty cool, with its
epicycles, deferents offset by an equants, and retrograde motions of
planets. Who says orbits need to be simple ellipses? :-D
http://en.wikipedia.org/wiki/Ptolemaic_system
Dislaimer: however, I don't think geocentrism is cool at all.
John Wilkins
> Lee Jay wrote:
> > dkomo wrote:
> >
> >>Lee Jay wrote:
> >>
> >>>I'll take none of the above, Bob.
> >>
> >>Heh. I'll take all of the above.
> >
> >
> > The difference between us getting the wrong answer and they guy that
> > actually got the wrong answer, is we can defend our choices. That, and
> > that we're getting the wrong answer on purpose! ;-)
> >
>
> I simply happen to think Ptolmaic astronomy was pretty cool, with its
> epicycles, deferents offset by an equants, and retrograde motions of
> planets. Who says orbits need to be simple ellipses? :-D
I call down upon thee the wrath of Mighty Kepler!
>
> http://en.wikipedia.org/wiki/Ptolemaic_system
>
>
> --dk...@cris.com
>
>
> Dislaimer: however, I don't think geocentrism is cool at all.
bullpup
He got an early start on Oktoberfest.
Boikat
Timberwoof
"George" <geo...@yourservice.com> wrote:
> "Timberwoof" <timberw...@infernosoft.com> wrote in message
> news:timberwoof.spam-51...@nnrp-virt.nntp.sonic.net...
> > In article <1168048531.4...@s80g2000cwa.googlegroups.com>,
> > "Lee Jay" <ljfi...@msn.com> wrote:
> >
> >> Martin Andersen wrote:
> >> > Yet, the barycenter of the earth/moon orbit is about 1707km below the
> >> > surface of
> >> > the Earth on average.
> >>
> >> Yep. And that's not at Earth's center. The CG of the whole solar
> >> system is inside the Sun, isn't it?
> >
> > Yes, but not in the Sun's center either.
And, in fact, not even in the center of the sun:
In article <1168061719.0...@42g2000cwt.googlegroups.com>,
"Lee Jay" <ljfi...@msn.com> wrote:
> > --
> > Timberwoof <me at timberwoof dot com> http://www.timberwoof.com
> > It's easy to say a war is so important your neighbor should go fight it
> > for you.
>
> Umm, after re-reading the OP question, I don't see where it was qualified
> that any of those bodys had to orbit from the center of the earth.
>
> George
Talk to Martin and Lee about that.
Mark VandeWettering
If only we had some kind of theory of gravitation, we could crunch the
numbers and figure this out.
Mark
>
> Lee Jay
>
Timberwoof
Mark VandeWettering <wett...@attbi.com> wrote:
Ouch!
rip...@azonic.co.nz
dkomo wrote:
> > It really is pathetic how little the general public knows of even very
> > basic science.
> If you stand on the moon, the earth appears to orbit the moon. And...
No it doesn't, it remains stationary (but rotating) at a fixed point in
the sky.
dkomo
I don't think the earth would be quite at a fixed point since the center
of gravity of the earth-moon system isn't exactly at the center of the
earth. You should be able to detect some jitter in the earth, and that
would be its (degenerate) orbit relative to the moon.
Free Lunch
nmp <add...@is.invalid> wrote in
<459ffaef$0$335$e4fe...@news.xs4all.nl>:
>Op Sat, 06 Jan 2007 09:00:50 -0500, schreef Umberto Ramirez:
>a common practice in most countries.
Civilized countries aren't as obsessed with their hypocrisy as the US
is. Vulgarities and obscenities have a place, sometimes unwelcome, in
any society. It happens, we go on. The US on the other hand, has
regressed so much that shows that were allowed on television a quarter
of a century ago are no longer allowed on without editing.
Timberwoof
dkomo <dkom...@comcast.net> wrote:
Degenerate? Elliptical, I'd say.
Timberwoof
rip...@Azonic.co.nz wrote:
Pretty much fixed, anyway, for the moon's orbit is elliptical but its
rotation is constant. It's the same effect as the figure 8 of the
Equation of Time.
http://images.google.com/images?client=safari&rls=en&q=equation%20of%20ti
me&ie=UTF-8&oe=UTF-8&sa=N&tab=wi
And oh, my, what I found there!
http://www.timezone.com/library/rdnotebook/200503287777
Boy, I wish I needed that.
Free Lunch
nmp <add...@is.invalid> wrote in
<45a02d9f$0$322$e4fe...@news.xs4all.nl>:
>Op Sat, 06 Jan 2007 15:14:23 -0600, schreef Free Lunch:
I doubt they were ever allowed to.
The program I was thinking of was I, Claudius, which had been run on PBS
without editing when it ran the same year that the Beeb ran it.
Umberto Ramirez
nmp <add...@is.invalid> wrote:
> Op Sat, 06 Jan 2007 09:00:50 -0500, schreef Umberto Ramirez:
>
> Why wouldn't they know it is a swear word?
Lighten up, dude. It was a joke.
>Beeping away such words is not
> a common practice in most countries.
Thanks for the edumacations.
jkrehbielp
I also remember the occupants of the Jupiter II suffering in the heat
of passing comets.
jkrehbielp
dkomo wrote:
> Lee Jay wrote:
>
> >
> >>Which of the four objects listed below orbits Earth?
> >>
> >>1) Moon
> >>2) Sun
> >>3) Mars
> >>4) Venus
> >
> >
> >
> > the Earth and Sun.
> >
> > Of course, even that isn't true if you want to get into multi-body
> > mechanics (which is a good way to get a headache).
> >
> > It really is pathetic how little the general public knows of even very
> > basic science.
> >
> >
>
> Heh. I'll take all of the above. It depends on what you use as a
> reference point. If you stand st the center of gravity, then the earth
> and moon both orbit around you. But...
>
> If you stand on the moon, the earth appears to orbit the moon. And...
>
> the stars in the heavens appear to orbit the earth, as the ancient
> astronomers discovered.
>
> It's all relative, as Einstein said. There is no absolute reference
> point in spacetime.
>
>
> --dk...@cris.com
But if you take the Earth as a statonary reference point, the stars
must be moving at many times the speed of light. I doubt Einstein would
have liked that very much. ;-)
rip...@azonic.co.nz
dkomo wrote:
The CoG of earth-moon is always exactly on a line between the CoG of
earth and CoG of moon, it isn't at a fixed point in the earth. That is,
the earth won't 'jitter' as it rotates on its axis, the common CoG will
lie under a different place on the earth as it rotates.
If you were in the exact centre of the moon as seen from the earth you
will be on that line along the CoGs and looking along that line the CoG
of the earth will always be exactly on that.
So no, the earth will _not_ appear to orbit the moon, it will be fixed
in the sky, and no, the earth won't 'jitter' as it rotates.
Now in fact the position of the earth is not entirely fixed as the
moon's orbit relative to the earth does vary slightly and it allows an
additional 3% of the surface to be viewed at different times compared
to an exact fixed relationship.
I thought your comments were comical in juxaposition to, and a response
to: "is pathetic how little the general public knows".
Timberwoof
"jkrehbielp" <jkreh...@gmail.com> wrote:
> dkomo wrote:
> > Lee Jay wrote:
> >
> > > Desertphile wrote:
> > >
> > >>Which of the four objects listed below orbits Earth?
> > >>
> > >>1) Moon
> > >>2) Sun
> > >>3) Mars
> > >>4) Venus
> > >
> > >
> > > I'll take none of the above, Bob.
> > >
> > > The Earth and Moon each orbit their collective center of gravity, as do
> > > the Earth and Sun.
> > >
> > > Of course, even that isn't true if you want to get into multi-body
> > > mechanics (which is a good way to get a headache).
> > >
> > > It really is pathetic how little the general public knows of even very
> > > basic science.
> > >
> > > Lee Jay
> > >
> >
> > Heh. I'll take all of the above. It depends on what you use as a
> > reference point. If you stand st the center of gravity, then the earth
> > and moon both orbit around you. But...
> >
> > If you stand on the moon, the earth appears to orbit the moon. And...
Nope, as has been pointed out elsewhere. (Home come we get to see only
one side of it?) (Well, a very clever person living on the Moon might
realize that the moon is rotating and that the Earth must therefore
orbit it at the same rate that the moon rotates ... and then soon
realize that the moon is orbiting the Earth.)
> > If you stand on the earth, the moon, sun, mars and venus, as well as all
> > the stars in the heavens appear to orbit the earth, as the ancient
> > astronomers discovered.
Well, they appear to go around the earth, but you can't use the
technical definition or orbit and say that.
> > It's all relative, as Einstein said. There is no absolute reference
> > point in spacetime.
That's not what Einstein said. (Galieo, Ernst Mach, Einstein, and others
had a lot of things to contribute to the principle, special theory, and
general theory of relativity, but that was not one of them.)
> But if you take the Earth as a statonary reference point, the stars
> must be moving at many times the speed of light. I doubt Einstein would
> have liked that very much. ;-)
--
Timberwoof
"jkrehbielp" <jkreh...@gmail.com> wrote:
I remember that once they visited a planet with a highly eccentric orbit
where the sun was at one focus instead of in the middle, which led to
very hot summers. (I didn't know enough back then to say, ahm, guys, ...
if you had spent just a few weeks plotting the position of that planet
as you approached it, you would have been able to determine all its
orbital parameters. Oh, and you're being stupid because nothing orbits
like that first "normal" example you gave.)
dkomo
> dkomo wrote:
>
>
>>>>>It really is pathetic how little the general public knows of even very
>>>>>basic science.
>>>
>>>>If you stand on the moon, the earth appears to orbit the moon. And...
>>>
>>>No it doesn't, it remains stationary (but rotating) at a fixed point in
>>>the sky.
>>
>>I don't think the earth would be quite at a fixed point since the center
>>of gravity of the earth-moon system isn't exactly at the center of the
>>earth. You should be able to detect some jitter in the earth, and that
>>would be its (degenerate) orbit relative to the moon.
>
>
> The CoG of earth-moon is always exactly on a line between the CoG of
> earth and CoG of moon, it isn't at a fixed point in the earth. That is,
> the earth won't 'jitter' as it rotates on its axis, the common CoG will
> lie under a different place on the earth as it rotates.
>
Eh? Forget about the rotation of the earth on its axis. We're talking
about the orbital motions of the moon and earth around their common
center of gravity.
"Jitter" was an imprecise word to use. What actually happens is that
the earth's center of gravity traces out a small elliptical orbit around
the center of gravity of the earth-moon system. Standing on the moon,
you should be able to detect this motion with the right instruments.
> If you were in the exact centre of the moon as seen from the earth you
> will be on that line along the CoGs and looking along that line the CoG
> of the earth will always be exactly on that.
>
> So no, the earth will _not_ appear to orbit the moon, it will be fixed
> in the sky, and no, the earth won't 'jitter' as it rotates.
>
By this argument, you wouldn't be able to see the orbital motion of the
moon from earth either. This is obviously an incorrect argument. My
"jitter" remark was about the earth's orbital motion and not its
rotation on its axis.
> Now in fact the position of the earth is not entirely fixed as the
> moon's orbit relative to the earth does vary slightly and it allows an
> additional 3% of the surface to be viewed at different times compared
> to an exact fixed relationship.
>
This is something different from orbital motion. I think it is caused
by the moon's period of rotation not being exactly equal to its period
of revolution around the earth, so that the one side of the moon doesn't
exactly face the earth at all times. This will produce a slight
"earthrise" and "earthset" effect as viewed from the moon.
"What is Earthrise over the Moon?"
http://curious.astro.cornell.edu/question.php?number=365
> I thought your comments were comical in juxaposition to, and a response
> to: "is pathetic how little the general public knows".
>
My original post was meant satirically, yes, but now we're having a
serious dispute about how the earth's motion appears from the viewpoint
of the moon. :-)
dkomo
> In article <E5ydndA6yZOckD3Y...@comcast.com>,
> dkomo <dkom...@comcast.net> wrote:
>
>
>>rip...@Azonic.co.nz wrote:
>>
>>
>>>dkomo wrote:
>>>
>>>
>>>
>>>>>It really is pathetic how little the general public knows of even very
>>>>>basic science.
>>>
>>>
>>>>If you stand on the moon, the earth appears to orbit the moon. And...
>>>
>>>
>>>No it doesn't, it remains stationary (but rotating) at a fixed point in
>>>the sky.
>>>
>>
>>I don't think the earth would be quite at a fixed point since the center
>>of gravity of the earth-moon system isn't exactly at the center of the
>>earth. You should be able to detect some jitter in the earth, and that
>>would be its (degenerate) orbit relative to the moon.
>
>
> Degenerate? Elliptical, I'd say.
>
Yes, elliptical. I probably should have said "nearly degenerate"
because the orbit would be so tiny. It would be completely degenerate
if the Cog of the earth-moon system coincided with the Cog of the earth,
so the earth's orbital path would collapse to a single point.
dkomo
How did you come up with this?
I doubt Einstein would
> have liked that very much. ;-)
>
Actually, there's nothing wrong with stars moving faster than light.
The galaxies beyond our Hubble sphere are in fact receding from us
faster than the speed of light. The speed of light is not a limit for
the expansion of spacetime.
Josh Hayes
news:timberwoof.spam-1C...@nnrp-virt.nntp.sonic.net:
[more "Lost in Space" idiocy snipped]
Probably the thing that chafed me most about this show, and remember, I was
only about 8 or 9 when it was on, was how the Robinsons would land on
ANOTHER PLANET, get out, see the locals, and shout, "Aliens!"
Yo, dumb-butts. YOU'RE the damn aliens. THEY live here. (Although they
might well be, say, big fat people singing opera badly and having odd
magical powers: I am not making this up.)
It's just this kind of human-centric thinking that makes IDers and the
other creationists act the way they do, he said, neatly bringing this back
more or less on topic. Hmph.
-JAH
three hours at the Seattle schools Kindergarten Fair today. The horror.
Klaus
> R. Baldwin <res0...@nozirevBACKWARDS.net> wrote:
>
>
>>"John Wilkins" <j.wil...@uq.edu.au> wrote in message
>>news:1hriumt.18dq5y9bkbop5N%j.wil...@uq.edu.au...
>>
>>>R. Baldwin <res0...@nozirevBACKWARDS.net> wrote:
>>>
>>>
>>>>"Free Lunch" <lu...@nofreelunch.us> wrote in message
>>>>news:n62up2tog3hbf8ddr...@4ax.com...
>>>>
>>>>>On Sat, 06 Jan 2007 01:49:04 +0000, in talk.origins
>>>>>Martin <use...@etiqa.co.uk> wrote in
>>>>><459f004b$0$27099$db0f...@news.zen.co.uk>:
>>>>>
>>>>>>
>>>>>>>Which of the four objects listed below orbits Earth?
>>>>>>>
>>>>>>>1) Moon
>>>>>>>2) Sun
>>>>>>>3) Mars
>>>>>>>4) Venus
>>>>>>>
>>>>>>>
>>>>>>>According to the French version of "Who Wants to be a Millionaire?"
>>>>>>>the
>>>>>>>answer is "Sacred blue! Fuckall if I know!" And France has The
>>>>>>>Bomb......
>>>>>>>
>>>>>>
>>>>>>rofl
>>>>>>
>>>>>>I'd give the 'correct' answer. "What's your frame of reference?"
>>>>>
>>>>>Boston, of course. It's the hub of the universe.
>>>>>
>>>>
>>>>No. Fremont, in Seattle, is the center of the Universe.
>>>
>>
>>What's this hub, bub?
>
>
> Sorry, I'm tyred of all this. I made an axle-dent, leave it at that.
You Otto leave it alone.
Klaus
rip...@azonic.co.nz
dkomo wrote:
> > The CoG of earth-moon is always exactly on a line between the CoG of
> > earth and CoG of moon, it isn't at a fixed point in the earth. That is,
> > the earth won't 'jitter' as it rotates on its axis, the common CoG will
> > lie under a different place on the earth as it rotates.
> Eh? Forget about the rotation of the earth on its axis. We're talking
> about the orbital motions of the moon and earth around their common
> center of gravity.
Which happens to _exactly_ coincide with the orbit of the moon around
that commeon centre and is, indeed, caused specifically by that. As I
said the common CoG is always exactly on the line between the two CoGs,
that line does not bend or twist, nor does the earth move to one side
of it or the other.
> "Jitter" was an imprecise word to use. What actually happens is that
> the earth's center of gravity traces out a small elliptical orbit around
> the center of gravity of the earth-moon system. Standing on the moon,
> you should be able to detect this motion with the right instruments.
No. Wrong. The line from the centre of the moon will always go
directly thru the common CoG and then to the exact CoG of the earth.
That is the CoG of the earth will always be directly away from the
moon along the line between the CoGs. The moon is orbiting the common
CoG at exactly the same speed as the earth orbits that common CoG, and
is in exactly the right direction to _always_ look _exactly_ along the
long axis of the 'small eliptical orbit' (which is nearly perfectly
circular).
That is, you will never get:
o ( CoG of earth )
( )
/
( moon ) -------------------------------------O ( common CoG )
( )
They will always be in a straight line with the CoGs of earth and moon
always on opposite sides of the common CoG. How hard is this ?
> By this argument, you wouldn't be able to see the orbital motion of the
> moon from earth either. This is obviously an incorrect argument. My
> "jitter" remark was about the earth's orbital motion and not its
> rotation on its axis.
The moon appears to orbit the earth due entirely to the earth's
rotation on its axis every 24 hours. So we get moon rise and moon set
approx every 24hr and 40min. The moon rotates on its axis at exactly
the same rate as it orbits the earth so that it always shows the same
face to the earth. If you were on one place on the moon there would be
no earth rise or earth set. It would remain apparently motionless in
the sky. You would, however, get sunrise and set and star rise and set
every 28 days or so.
If the earth rotated once every 28 days or so and was in sync with the
moon, then no, you would not be able to see the moon 'orbit' the common
CoG.
> > Now in fact the position of the earth is not entirely fixed as the
> > moon's orbit relative to the earth does vary slightly and it allows an
> > additional 3% of the surface to be viewed at different times compared
> > to an exact fixed relationship.
>
> This is something different from orbital motion. I think it is caused
> by the moon's period of rotation not being exactly equal to its period
> of revolution around the earth, so that the one side of the moon doesn't
> exactly face the earth at all times.
No. Wrong. The two are exactly equal. Being able to see fractionally
different areas is entirely due to variations in the ecliptic over the
year.
If the two were not equal exactly then the face would continue to
change over long periods of time.
> This will produce a slight
> "earthrise" and "earthset" effect as viewed from the moon.
Well obviously there will be places on the edge of the face we see that
sometimes could see part of the earth and sometimes not but the change
takes months.
> "What is Earthrise over the Moon?"
>
> http://curious.astro.cornell.edu/question.php?number=365
<shrug> I've seen the sun rise in the west. We took off a couple of
minutes after the sun set and then climbed to 35,000 ft cruising
altitude. The climb resulted in the angle to the ever increasing
horizon changing faster than the 15 degrees per hour the sun was
setting at and so the sun went from completely set to completely above
the horizon. It had sun-dogs too, and me without a camera.
> > I thought your comments were comical in juxaposition to, and a response
> > to: "is pathetic how little the general public knows".
> >
>
> My original post was meant satirically, yes,
Should I doubt that ? The tone certainly did not indicate anything
other than a complete blunder.
> but now we're having a
> serious dispute about how the earth's motion appears from the viewpoint
> of the moon. :-)
Well, I am discussing it seriously, certainly.
rip...@azonic.co.nz
rip...@Azonic.co.nz wrote:
> > "Jitter" was an imprecise word to use. What actually happens is that
> > the earth's center of gravity traces out a small elliptical orbit around
> > the center of gravity of the earth-moon system. Standing on the moon,
> > you should be able to detect this motion with the right instruments.
Further to that, if you were somewhere other than the moon and was in a
fixed position relative to the earth (eg orbitting the sun at the same
rate as the earth) then you would be able to detect the earth orbitting
the common CoG with the moon by it being displaced 'sideways' several
1000km on a 28 day cycle. But you cannot detect that from the moon
because the displacement is always exactly away from the moon.
rip...@azonic.co.nz
dkomo wrote:
> > But if you take the Earth as a statonary reference point, the stars
> > must be moving at many times the speed of light.
>
> How did you come up with this?
If the earth was stationary and the star is 4.3 light years away then
its path would be 4.3 x 2 x pi long (27) light years which it would
travel in each 24 hours. And that is the second closest star.
SeppoP
<snip>
>
> And oh, my, what I found there!
>
> http://www.timezone.com/library/rdnotebook/200503287777
>
> Boy, I wish I needed that.
>
Now, there's a *real* analog computer...
--
Seppo P.
What's wrong with Theocracy? (a Finnish Taliban, Oct 1, 2005)
dkomo
Ah, yes. Because the stars appear to travel across the sky in a single
night, they would have to be moving faster than the speed of light. So
this is solid evidence that it must be the earth which is rotating.
There's just one little thing that bothers me about this argument. It's
not compatible with relativity. When two observers are moving relative
to each other, it shouldn't be possible for one to tell that it is *he*
that is moving while the other is standing still. Above, we concluded
that the earth must be moving while the stars, for all practical
purposes, are standing still.
Ernest Major
<dkom...@comcast.net> writes
reference frame with respect to linear (and unaccelerated) motion.
Special Relativity still allows us to identify rotational and
accelerated motion.
--
alias Ernest Major
dkomo
But I never said "special relativity". I said "relativity".
In general relativity accelerated motion and gravity are equivalent. So
there should be no way for an observer to tell if he's moving, whether
that motion is linear or accelerated.
rip...@azonic.co.nz
dkomo wrote:
> >>>But if you take the Earth as a statonary reference point, the stars
> >>>must be moving at many times the speed of light.
> >>
> >>How did you come up with this?
> >
> > If the earth was stationary and the star is 4.3 light years away then
> > its path would be 4.3 x 2 x pi long (27) light years which it would
> > travel in each 24 hours. And that is the second closest star.
>
> Ah, yes. Because the stars appear to travel across the sky in a single
> night, they would have to be moving faster than the speed of light. So
> this is solid evidence that it must be the earth which is rotating.
I don't see a claim for the conclusion that _you_ draw.
> There's just one little thing that bothers me about this argument. It's
> not compatible with relativity.
What is 'not compatible' ? The argument or _your_ conclusion ?
> When two observers are moving relative
> to each other, it shouldn't be possible for one to tell that it is *he*
> that is moving while the other is standing still. Above, we concluded
> that the earth must be moving while the stars, for all practical
> purposes, are standing still.
"We" didn't conclude, you did.
Timberwoof
dkomo <dkom...@comcast.net> wrote:
Well, what you say is true for rectilinear motion, but that's not what's
happening here.
Timberwoof
dkomo <dkom...@comcast.net> wrote:
But then the Earth and Moon would be a single planet, not two. In the
context of astronomy, what's a degenerate orbit?
dkomo
> In article <_IGdnTKY5p0tGz3Y...@comcast.com>,
> dkomo <dkom...@comcast.net> wrote:
>
>
>>Timberwoof wrote:
>>
>>
>>>In article <E5ydndA6yZOckD3Y...@comcast.com>,
>>> dkomo <dkom...@comcast.net> wrote:
>>>
>>>
>>>
>>>>rip...@Azonic.co.nz wrote:
>>>>
>>>>
>>>>
>>>>>dkomo wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>>It really is pathetic how little the general public knows of even very
>>>>>>>basic science.
>>>>>
>>>>>
>>>>>>If you stand on the moon, the earth appears to orbit the moon. And...
>>>>>
>>>>>
>>>>>No it doesn't, it remains stationary (but rotating) at a fixed point in
>>>>>the sky.
>>>>>
>>>>
>>>>I don't think the earth would be quite at a fixed point since the center
>>>>of gravity of the earth-moon system isn't exactly at the center of the
>>>>earth. You should be able to detect some jitter in the earth, and that
>>>>would be its (degenerate) orbit relative to the moon.
>>>
>>>
>>>Degenerate? Elliptical, I'd say.
>>>
>>
>>Yes, elliptical. I probably should have said "nearly degenerate"
>>because the orbit would be so tiny. It would be completely degenerate
>>if the Cog of the earth-moon system coincided with the Cog of the earth,
>>so the earth's orbital path would collapse to a single point.
>
>
> But then the Earth and Moon would be a single planet, not two.
No, it is simply the limiting case where one body in a two-body problem
is much more massive than the other. For the solar system, the sun is
so massive relative to the planets it hardly moves at all as the planets
circle around it.
In the
> context of astronomy, what's a degenerate orbit?
>
Degenerate simply means "limiting case". For example, a circle is a
"degenerate" ellipse with an eccentricity of 1. A white dwarf is a
collapsed degenerate star. A satellite whose orbit degenerates plunges
into the atmosphere and burns up.
dkomo
> In article <GvednT56I7ZwkjzY...@comcast.com>,
> dkomo <dkom...@comcast.net> wrote:
>
>
>>rip...@Azonic.co.nz wrote:
>>
>>>dkomo wrote:
>>>
>>>
>>>
>>>>>But if you take the Earth as a statonary reference point, the stars
>>>>>must be moving at many times the speed of light.
>>>>
>>>>How did you come up with this?
>>>
>>>
>>>If the earth was stationary and the star is 4.3 light years away then
>>>its path would be 4.3 x 2 x pi long (27) light years which it would
>>>travel in each 24 hours. And that is the second closest star.
>>>
>>
>>Ah, yes. Because the stars appear to travel across the sky in a single
>>night, they would have to be moving faster than the speed of light. So
>>this is solid evidence that it must be the earth which is rotating.
>>
>>There's just one little thing that bothers me about this argument. It's
>>not compatible with relativity. When two observers are moving relative
>>to each other, it shouldn't be possible for one to tell that it is *he*
>>that is moving while the other is standing still. Above, we concluded
>>that the earth must be moving while the stars, for all practical
>>purposes, are standing still.
>
>
> Well, what you say is true for rectilinear motion, but that's not what's
> happening here.
>
See my reply to Ernest Major.
dkomo
What you are saying is absurd.
Look, consider a binary star system consisting of two equally massive
stars, Romulus and Remus. These two stars would orbit around their CG,
which is exactly halfway between. According to your logic, if you stood
on Remus, you would not be able to detect the orbital motion of Romulus.
In fact, if you stood on Remus, you would see both the CG and Romulus
orbiting around *you*.
Now keep increasing the mass of one of them, say Romulus. The CG moves
closer and closer to Romulus, but if you're standing on Remus, you still
see the orbital motion of both the CG and Romulus around you.
dkomo
Well, since you're such a frackin' genius, as is evident from the rest
of your posts, please enlighten us with what conclusion *you* would draw
from the apparent motion of the stars across the night sky.
John Bode
Free Lunch wrote:
> On 06 Jan 2007 19:39:27 GMT, in talk.origins
> nmp <add...@is.invalid> wrote in
> <459ffaef$0$335$e4fe...@news.xs4all.nl>:
> >Op Sat, 06 Jan 2007 09:00:50 -0500, schreef Umberto Ramirez:
> >
> >> In article <INGdnSmFJ5FUAgLY...@comcast.com>,
> >> "Geoff" <ge...@nospam.com> wrote:
> >
> >>> I swear he says, "Merde" when they reveal the answer.
> >>
> >> And that wasn't even one of the choices!
> >>
> >> (but yeah, I think he did say that - maybe they didn't know it was a
> >> swear word)
> >
> >Why wouldn't they know it is a swear word? Beeping away such words is not
> >a common practice in most countries.
>
> Civilized countries aren't as obsessed with their hypocrisy as the US
> is. Vulgarities and obscenities have a place, sometimes unwelcome, in
> any society. It happens, we go on. The US on the other hand, has
> regressed so much that shows that were allowed on television a quarter
> of a century ago are no longer allowed on without editing.
Are you kidding? Have you *seen* shows like CSI?
rip...@azonic.co.nz
dkomo wrote:
> rip...@Azonic.co.nz wrote:
>
> > rip...@Azonic.co.nz wrote:
> >>>"Jitter" was an imprecise word to use. What actually happens is that
> >>>the earth's center of gravity traces out a small elliptical orbit around
> >>>the center of gravity of the earth-moon system. Standing on the moon,
> >>>you should be able to detect this motion with the right instruments.
> >
> > Further to that, if you were somewhere other than the moon and was in a
> > fixed position relative to the earth (eg orbitting the sun at the same
> > rate as the earth) then you would be able to detect the earth orbitting
> > the common CoG with the moon by it being displaced 'sideways' several
> > 1000km on a 28 day cycle. But you cannot detect that from the moon
> > because the displacement is always exactly away from the moon.
>
> What you are saying is absurd.
Is it your claim that the displacement of the earth away from to common
CoG is _not_ always exactly away from the moon ?
> Look, consider a binary star system consisting of two equally massive
> stars, Romulus and Remus. These two stars would orbit around their CG,
> which is exactly halfway between. According to your logic, if you stood
> on Remus, you would not be able to detect the orbital motion of Romulus.
>
> In fact, if you stood on Remus, you would see both the CG and Romulus
> orbiting around *you*.
> Now keep increasing the mass of one of them, say Romulus. The CG moves
> closer and closer to Romulus, but if you're standing on Remus, you still
> see the orbital motion of both the CG and Romulus around you.
Do you have an image of sitting on the moon and sometime the earth is
to the left of the common CoG and sometimes it is to the right as it
orbits the common CoG ? How frequent will that cycle be ?
Or do you imagine that sitting on the moon you will see an earthrise
and an earthset. How often will you see these ?
If you see the earth orbitting the common CoG will it pass between the
moon and the common CoG in its orbit ?
What was it you claimed was 'absurd ?
rip...@azonic.co.nz
dkomo wrote:
> >> When two observers are moving relative
> >>to each other, it shouldn't be possible for one to tell that it is *he*
> >>that is moving while the other is standing still. Above, we concluded
> >>that the earth must be moving while the stars, for all practical
> >>purposes, are standing still.
> Well, since you're such a frackin' genius, as is evident from the rest
> of your posts, please enlighten us with what conclusion *you* would draw
> from the apparent motion of the stars across the night sky.
Have you sorted out your argument with relativity yet ? Can you tell or
can't you ?
I wouldn't conclude, based on this, that the earth is moving, I may
examine much other evidence and decide that it is rotating.
The problem with 'moving' is that it would have to travel as fast as
the objects that appear to be going the other way.
Free Lunch
"John Bode" <john...@my-deja.com> wrote in
<1168271753.9...@s80g2000cwa.googlegroups.com>:
This is America. Violence, even sexually oriented violence, is okay in
any setting.
A nipple, even appropriately shown, can cost each television station
thousands in fines. A gory evisceration of a human won't cause the FCC
any trouble at all.
Gerry Murphy
"Free Lunch" <lu...@nofreelunch.us> wrote in message
news:n62up2tog3hbf8ddr...@4ax.com...
> On Sat, 06 Jan 2007 01:49:04 +0000, in talk.origins
> Martin <use...@etiqa.co.uk> wrote in
> <459f004b$0$27099$db0f...@news.zen.co.uk>:
> >Desertphile wrote:
> >> Which of the four objects listed below orbits Earth?
> >>
> >> 1) Moon
> >> 2) Sun
> >> 3) Mars
> >> 4) Venus
> >>
> >> http://tinyurl.com/yhjyew
> >>
> >> According to the French version of "Who Wants to be a Millionaire?" the
> >> answer is "Sacred blue! Fuckall if I know!" And France has The
> >> Bomb......
> >>
> >rofl
> >
> >I'd give the 'correct' answer. "What's your frame of reference?"
>
> Boston, of course. It's the hub of the universe.
Right on. Go Sox! 8-}
George
"Josh Hayes" <jos...@spamblarg.net> wrote in message
news:Xns98B0E1DBA73...@216.168.3.44...
Do I dare say it?.....
Oh the pain! The pain!
George
Timberwoof
"George" <geo...@yourservice.com> wrote:
Captain! I detect ... bad acting!
George
"Timberwoof" <timberw...@infernosoft.com> wrote in message
news:timberwoof.spam-98...@nnrp-virt.nntp.sonic.net...
> In article <0K4ph.45$t6...@bignews8.bellsouth.net>,
> "George" <geo...@yourservice.com> wrote:
>
>> "Josh Hayes" <jos...@spamblarg.net> wrote in message
>> news:Xns98B0E1DBA73...@216.168.3.44...
>> > Timberwoof <timberw...@infernosoft.com> wrote in
>> > news:timberwoof.spam-1C...@nnrp-virt.nntp.sonic.net:
>> >
>> > [more "Lost in Space" idiocy snipped]
>> >
>> > Probably the thing that chafed me most about this show, and remember,
>> > I
>> > was
>> > only about 8 or 9 when it was on, was how the Robinsons would land on
>> > ANOTHER PLANET, get out, see the locals, and shout, "Aliens!"
>> >
>> > Yo, dumb-butts. YOU'RE the damn aliens. THEY live here. (Although they
>> > might well be, say, big fat people singing opera badly and having odd
>> > magical powers: I am not making this up.)
>> >
>> > It's just this kind of human-centric thinking that makes IDers and the
>> > other creationists act the way they do, he said, neatly bringing this
>> > back
>> > more or less on topic. Hmph.
>> >
>> > -JAH
>>
>> Do I dare say it?.....
>>
>> Oh the pain! The pain!
>>
>> George
>
> Captain! I detect ... bad acting!
Dr. Smith: Silence, you ninny.
Ugh!
George
Geoff
This is definitely true, but we were talking about vulgarity. In any case,
cable has taken the lead on honest television and we can have our
linguistically-clean but content-free and violence-laden programming for
kids and Christians segregated on network.
Free Lunch
"Geoff" <ge...@nospam.com> wrote in
<6aqdnc4bgMY1GTbY...@comcast.com>:
As I recall, vulgar words are still forbidden.
jkrehbielp
Timberwoof wrote:
> I remember that once they visited a planet with a highly eccentric orbit
> where the sun was at one focus instead of in the middle, which led to
> very hot summers.
Erm.. The Sun is _supposed_ to be at a focus. It's the eccentricity
that was a problem.
BTW, the Earth is closer to the sun Jan 4th than during Northern
Hemisphere summer. It's the tilt of the axis that causes seasons. Of
course a very highly eccentric orbit would make the distance effect
more important.
SeppoP
Ahh, yes. Vulgar words and dysfunctional nipple covers. Defending against *those* are the *true* cornerstones of the
"Western Christian Morality"... Isn't it great that we *finally* found out where the *real* evil resides...
Timberwoof
"jkrehbielp" <jkreh...@gmail.com> wrote:
> Timberwoof wrote:
> > I remember that once they visited a planet with a highly eccentric orbit
> > where the sun was at one focus instead of in the middle, which led to
> > very hot summers.
>
> Erm.. The Sun is _supposed_ to be at a focus. It's the eccentricity
> that was a problem.
Yes, it is supposed to be at the focus, not at the middle. That's one
point. The guy drew a highly elliptical orbit with a star in the middle:
(=====*=====)
and said that this was usual. Then he showed "this" planet's orbit:
(*==========)
and pointed out that it was in for a hot summer.
> BTW, the Earth is closer to the sun Jan 4th than during Northern
> Hemisphere summer. It's the tilt of the axis that causes seasons. Of
> course a very highly eccentric orbit would make the distance effect
> more important.
The eccentricity of the Earth's orbit is negligible compared to what
they were showing, one of which resembled a cometary orbit.
--
Timberwoof <me at timberwoof dot com> http://www.timberwoof.com
"Like this cup," the master daid, "you are full of your own opinions and
speculations. How can I show you anything unless you first empty your cup?"
Kermit
rip...@Azonic.co.nz wrote:
> dkomo wrote:
>
> > >> When two observers are moving relative
> > >>to each other, it shouldn't be possible for one to tell that it is *he*
> > >>that is moving while the other is standing still. Above, we concluded
> > >>that the earth must be moving while the stars, for all practical
> > >>purposes, are standing still.
>
> > Well, since you're such a frackin' genius, as is evident from the rest
> > of your posts, please enlighten us with what conclusion *you* would draw
> > from the apparent motion of the stars across the night sky.
>
> Have you sorted out your argument with relativity yet ? Can you tell or
> can't you ?
>
> I wouldn't conclude, based on this, that the earth is moving, I may
> examine much other evidence and decide that it is rotating.
So you don't consider rotation to be movement? I think most people
would, which would explain some of the posts and replies here.
>
> The problem with 'moving' is that it would have to travel as fast as
> the objects that appear to be going the other way.
Kermit
rip...@azonic.co.nz
Kermit wrote:
> rip...@Azonic.co.nz wrote:
> > dkomo wrote:
> >
> > > >> When two observers are moving relative
> > > >>to each other, it shouldn't be possible for one to tell that it is *he*
> > > >>that is moving while the other is standing still. Above, we concluded
> > > >>that the earth must be moving while the stars, for all practical
> > > >>purposes, are standing still.
> >
> > > Well, since you're such a frackin' genius, as is evident from the rest
> > > of your posts, please enlighten us with what conclusion *you* would draw
> > > from the apparent motion of the stars across the night sky.
> >
> > Have you sorted out your argument with relativity yet ? Can you tell or
> > can't you ?
> >
> > I wouldn't conclude, based on this, that the earth is moving, I may
> > examine much other evidence and decide that it is rotating.
>
> So you don't consider rotation to be movement? I think most people
> would, which would explain some of the posts and replies here.
The two are not synonymous. Moving is not rotating. If we consider the
refernce to be the position of the earth then _we_ on the surface are
moving up to 1000mph (depending where we are on the surface), but the
_earth_ is just rotating (and not moving). I would suggest that your
'most people' are confused between rotating and moving for that very
reason: the _surface_ is moving, the _earth_ is rotating.
dkomo had established the context he was using for the word with
"moving relative to each other". Of course the Earth is _also_ moving:
along its orbital path; as part of the solar system as the galaxy
rotates; as part of the galaxy. But one cannot conclude that it is
moving (travelling) that way based on the daily apparent motion of the
stars - other evidence is necessary.
dmoko still hasn't explained what he thinks that he would see from the
moon concerning the earth orbitting its common CoG with the moon.
Apparently he thinks that the CoG of the earth could pass between the
moon and their common CoG.
jensp...@hotmail.com
dkomo wrote:
> What you are saying is absurd.
Sorry, to say so , but you are wrong. It's as simple and plain as that,
and you have been given all the right explanations by riplin.
I'll suggest that you sit down with an open mind to understand and
learn, and then reads his posts again.
J.O.
dkomo
I hadn't checked this thread for some time because I thought it was
dead, but this afternoon I noticed it still had life (other than the
endless drivel cascades in subthreads).
I gave you a simple example of the binary star system but you ignored it
and simply came back with your usual doubletalk and a set of new
questions for me.
Ok, let's try something else. I claim what you are saying is absurd
because there is an easy, empirical counterexample to it. Consider the
sun-earth system. Humans have been studying the heavens for thousands
of years and one of the things they discovered was that the sun appears
to travel along a path called the elliptic relative to the fixed stars,
completing a full path in exactly one year. These ancient peoples were
not aware that it was actually the earth that was revolving around the sun.
Thus we have the houses of the Zodiac which are familiar constellations
arrayed in a 360 degree panorama across the night sky. The sun as it
makes its yearly circle moves from one house of the zodiac to the next.
Thus, the sun's apparent orbit is clearly observable from the earth.
Now, explain to me, without lapsing into your usual bullshit, what
exactly is the difference between the earth-sun system, where the sun
appears to orbit the earth, and the earth-moon system, where you claim
that the earth's apparent orbit would be undetectable from the moon.
Note the close analogy here. The sun is much more massive than the
earth, and the CG is very nearly at the sun. The earth is substantially
more massive than the moon, and the CG is in fact inside the earth.
Explain clearly just what exactly it is that makes the sun's apparent
motion so easily detectable from the earth, while the earth's apparent
motion would not be detectable from the moon. I want to know *exactly*
what the differences are.
Hint: *do not even mention* the rotation of the earth on its axis, and
the moon on its axis, because these are completely irrelevant to a
general two-body system revolving around their CG.
rip...@azonic.co.nz
> and simply came back with your usual doubletalk and a set of new
> questions for me.
Questions which you have not answered. The point about asking them was
to attempt to get you to _think_ about the situation.
> Ok, let's try something else. I claim what you are saying is absurd
> because there is an easy, empirical counterexample to it. Consider the
> sun-earth system. Humans have been studying the heavens for thousands
> of years and one of the things they discovered was that the sun appears
> to travel along a path called the elliptic relative to the fixed stars,
> completing a full path in exactly one year. These ancient peoples were
> not aware that it was actually the earth that was revolving around the sun.
>
> Thus we have the houses of the Zodiac which are familiar constellations
> arrayed in a 360 degree panorama across the night sky. The sun as it
> makes its yearly circle moves from one house of the zodiac to the next.
> Thus, the sun's apparent orbit is clearly observable from the earth.
No. That does not show "the Sun's apparent orbit around the common CoG
with the Earth" (which is the actual equivalent). It does show that the
Earth is orbiting the Sun, or possibly that all the stars are orbitting
the Sun and/or Earth. It does not show that the Sun is orbitting
anything. The "Sun's apparent orbit" is due to the Earth's daily
rotation.
> Now, explain to me, without lapsing into your usual bullshit, what
> exactly is the difference between the earth-sun system, where the sun
> appears to orbit the earth,
The Sun appears to orbit the Earth due to Earth's rotation.
> and the earth-moon system, where you claim
> that the earth's apparent orbit would be undetectable from the moon.
Sitting in the Moon one would see the background stars move once per 28
days or so.
> Note the close analogy here. The sun is much more massive than the
> earth, and the CG is very nearly at the sun. The earth is substantially
> more massive than the moon, and the CG is in fact inside the earth.
>
> Explain clearly just what exactly it is that makes the sun's apparent
> motion so easily detectable from the earth, while the earth's apparent
> motion would not be detectable from the moon. I want to know *exactly*
> what the differences are.
You are confusing two things. The apparent motion of the Sun across
the background due to the Earth's orbit and the actual orbit of the Sun
around its common CoG with the Earth.
> Hint: *do not even mention* the rotation of the earth on its axis, and
> the moon on its axis, because these are completely irrelevant to a
> general two-body system revolving around their CG.
You should also note that there is _no_ 'apparent orbit of the Earth
around the Moon'. The background stars appear to orbit the Moon but
the Earth is almost exactly stationary in the Moon's 'sky'.
This is what you claimed:
>"Jitter" was an imprecise word to use. What actually happens is that
>the earth's center of gravity traces out a small elliptical orbit around
>the center of gravity of the earth-moon system. Standing on the moon,
>you should be able to detect this motion with the right instruments.
Your claim is that you would see the 'small eliptical orbit' of the
Earth around the common CoG. This is not the apparent movement against
the background stars which is due to the Moon's orbit around the Earth
(or actually its common CoG).
If we assume that the common CoG is a fixed point then you may see the
'small eliptical orbit' if sometimes the Earth were towards the left of
it and sometime it were towards the right, sometime behind, and
sometimes in front of it. So you _would_ see that motion if, for
example, you were observing it from another fixed point. However from
the Moon the three points: Moon CoG, coom CoG and Earth CoG are always
in a single straight line (clue: this is _not_ absurd), the Earth will
never be 'a little bit to left or right', you will never see the 'small
eliptical orbit of the Earth around the common CoG'.
Certainly it exists, but from the Moon you cannot observe it because
the Earth is always on the path of that orbit directly away from the
Moon.
Even with your two star system there is no observable difference
between them being the same mass, or either one being much more
massive. The background would move smoothly past in the same way
regardless. It is not possible to observe which is orbitting the other
based on what you see of the other from either one of them.
rip...@azonic.co.nz
rip...@Azonic.co.nz wrote:
> Even with your two star system there is no observable difference
> between them being the same mass, or either one being much more
> massive. The background would move smoothly past in the same way
> regardless. It is not possible to observe which is orbitting the other
> based on what you see of the other from either one of them.
Further to that, if both faced each other as the Moon faces the Earth
(ie the orbits and rotations were in sync as the Moon's are) then there
would be _no_ 'apparent orbitting' of one around the other, just the
apparent orbitting of the background stars around whichever one you are
on..
Don Cates
posted:
The sun's appearant motion along the ecliptic has nothing to do with
your claim. Try this: Imagine that gravity does not work the way we
know it does, or perhaps imagine a massless Earth. So the CG
coresponds to the centre of the sun. How would the path of the sun
through the ecliptic change from what we presently see?
--
Don Cates ("he's a cunning rascal" - PN)
dkomo
The problem here is that I see these two apparent motions (earth and
stars) as equivalent. You don't.
Picture 1:
You're sitting on the moon. At different points in the moon's 28 day
orbit you see the earth at different points against the *fixed* stars.
In this picture the stars provide a fixed reference point. The earth is
apparently orbiting you.
Picture 2(yours):
You're sitting on the moon. At different points in the moon's 28 day
orbit you see the stars move against the earth, which is fixed in the
sky above you. In this picture the earth provides a fixed reference
point. The stars are apparently orbiting you, as you said above.
For some reason you're fixated on Picture 2. Hence I made my famous
"absurd" remark when you said you couldn't detect the earth's orbital
motion from the moon. You can if you choose Picture 1, and this is
entirely analogous to the sun's apparent orbital motion relative to the
fixed stars as seen from the earth, or the case of the binary star system.
This is also similar to case of two trains passing each other in
opposite directions. If there's no vibration and you're sitting in
train A (and you didn't already know that train A was moving), you can't
tell if your train is the one that is moving, or train B is moving, or both.
Here it is again graphically(sort of):
day 0:
( moon ) ------------------------O (earth) --------> (star A)
day 7 (assume 90 degree revolution of moon in its orbit as seen by an
observer in space):
(moon)
|
|
|
|
|
(earth)
|
|
|
|
|
\/
(star B)
Did the heavens apparently rotate so that star B has rotated into star
A's position, or did the earth apparently revolve in its ORBIT AROUND
THE MOON [emphasis added].
I'm beginning to think that we have been arguing about nothing other
than semantics all this time.
rip...@azonic.co.nz
dkomo wrote:
> The problem here is that I see these two apparent motions (earth and
> stars) as equivalent. You don't.
>
> Picture 1:
>
> You're sitting on the moon. At different points in the moon's 28 day
> orbit you see the earth at different points against the *fixed* stars.
> In this picture the stars provide a fixed reference point. The earth is
> apparently orbiting you.
>
> Picture 2(yours):
>
> You're sitting on the moon. At different points in the moon's 28 day
> orbit you see the stars move against the earth, which is fixed in the
> sky above you. In this picture the earth provides a fixed reference
> point. The stars are apparently orbiting you, as you said above.
I am pleased that you actually recognise that the Earth will be fixed
in the 'sky' of the Moon, but while the stars (including the Sun) _do_
apparently orbit the Moon, the Earth does not, neither in reality nor
apparently. No more so than the street light that you might be sitting
under. Both the street light and the Earth will be fixed above you,
does the street light also orbit you ?
> For some reason you're fixated on Picture 2. Hence I made my famous
> "absurd" remark when you said you couldn't detect the earth's orbital
> motion from the moon. You can if you choose Picture 1, and this is
> entirely analogous to the sun's apparent orbital motion relative to the
> fixed stars as seen from the earth, or the case of the binary star system.
Unfortunately this has nothing to do with what you claimed.
>"Jitter" was an imprecise word to use. What actually happens is that
>the earth's center of gravity traces out a small elliptical orbit around
>the center of gravity of the earth-moon system. Standing on the moon,
>you should be able to detect this motion with the right instruments.
So the apparent orbit of the stars around the Moon has nothing to do
with the 8000 km actual orbit of the Earth around its common CoG. I am
still waiting for you to tell me what you would see of this motion.
> This is also similar to case of two trains passing each other in
> opposite directions. If there's no vibration and you're sitting in
> train A (and you didn't already know that train A was moving), you can't
> tell if your train is the one that is moving, or train B is moving, or both.
You can rant on about trains and stars, but these have nothing to do
with the "small elliptical orbit around the center of gravity of the
earth-moon system."
rip...@azonic.co.nz
dkomo wrote:
> The problem here is that I see these two apparent motions (earth and
> stars) as equivalent. You don't.
>
> Picture 1:
>
> You're sitting on the moon. At different points in the moon's 28 day
> orbit you see the earth at different points against the *fixed* stars.
> In this picture the stars provide a fixed reference point. The earth is
> apparently orbiting you.
> This is also similar to case of two trains passing each other in
> opposite directions. If there's no vibration and you're sitting in
> train A (and you didn't already know that train A was moving), you can't
> tell if your train is the one that is moving, or train B is moving, or both.
The problem with 'picture 1' that you fail to see (other than it has
nothing to do with your claim) is that it is the light in the ceiling
above where you sit that you say is moving past you.
dkomo
Which claim? The sun's apparent motion has *everything* to do with my
main claim, which is that apparent orbital motions depend on the point
of observation. In one case the earth orbits the sun, but seen from the
earth, it is the sun orbiting the earth. In one case the moon orbits
the earth, but seen from the moon, it is the earth orbiting the moon.
Try this: Imagine that gravity does not work the way we
> know it does, or perhaps imagine a massless Earth. So the CG
> coresponds to the centre of the sun. How would the path of the sun
> through the ecliptic change from what we presently see?
This is too tricky a dynamics problem. If the earth became massless,
for example, it would fly off into space (no more attraction from the
sun). If you gradually reduced the mass of the earth, its orbit around
the sun would change, which would affect the cycle time of the path of
the sun through the ecliptic.
rip...@azonic.co.nz
dkomo wrote:
> > The sun's appearant motion along the ecliptic has nothing to do with
> > your claim.
>
> Which claim?
> >>>>>>>"Jitter" was an imprecise word to use. What actually happens is that
> >>>>>>>the earth's center of gravity traces out a small elliptical orbit around
> >>>>>>>the center of gravity of the earth-moon system. Standing on the moon,
> >>>>>>>you should be able to detect this motion with the right instruments.
Which either you now completely ignore or simply 'forget' even though
it is pointed out several times.
> The sun's apparent motion has *everything* to do with my
> main claim, which is that apparent orbital motions depend on the point
> of observation. In one case the earth orbits the sun, but seen from the
> earth, it is the sun orbiting the earth.
The apparent 'Sun orbitting the Earth' is entirely due to the Earth's
rotation and is not related to the Earth's actual orbit of the Sun.
> In one case the moon orbits
> the earth, but seen from the moon, it is the earth orbiting the moon.
If you were standing on a station with a train standing next to the
platform and you spun on one heel then the train may appear to 'orbit'
you, but from the train you are just spinning around.
>From the train your spinning will _not_ appear to be 'orbitting the
train'.
> This is too tricky a dynamics problem. If the earth became massless,
> for example, it would fly off into space (no more attraction from the
> sun).
That maybe hypothetically true. But if it were massless then it would
have no inertia (hypothetically) and could zig zag in a brownarian
motion.
> If you gradually reduced the mass of the earth, its orbit around
> the sun would change,
No. That is incorrect. The orbit is a function of the distance not the
mass.
Evidence for this is easy to obtain. The asteroids in the belt all
orbit at the same rate regardless of their individual mass.
> which would affect the cycle time of the path of
> the sun through the ecliptic.
No.
Don Cates
posted:
>Don Cates wrote:
>
>> On Mon, 15 Jan 2007 18:07:55 -0700, dkomo <dkom...@comcast.net>
>> posted:
>>
>>
>>>rip...@Azonic.co.nz wrote:
>>>
>>>
>>>>dkomo wrote:
>>>>
>>>>
>>>>>rip...@Azonic.co.nz wrote:
>>>>>
>>>>>
>>>>>
>>>>>>rip...@Azonic.co.nz wrote:
>>>>>>
>>>>>>
----------------Your first claim----------------
>>>>>>>>"Jitter" was an imprecise word to use. What actually happens is that
>>>>>>>>the earth's center of gravity traces out a small elliptical orbit around
>>>>>>>>the center of gravity of the earth-moon system. Standing on the moon,
>>>>>>>>you should be able to detect this motion with the right instruments.
-----------------------------------------------------
>>>>>>
>>>>>>Further to that, if you were somewhere other than the moon and was in a
>>>>>>fixed position relative to the earth (eg orbitting the sun at the same
>>>>>>rate as the earth) then you would be able to detect the earth orbitting
>>>>>>the common CoG with the moon by it being displaced 'sideways' several
>>>>>>1000km on a 28 day cycle. But you cannot detect that from the moon
>>>>>>because the displacement is always exactly away from the moon.
>>>>>
-------------Your second claim--------------
>>>>>What you are saying is absurd.
>>>>
-----------------------------------------------------
See above.
>main claim, which is that apparent orbital motions depend on the point
>of observation. In one case the earth orbits the sun, but seen from the
>earth, it is the sun orbiting the earth. In one case the moon orbits
>the earth, but seen from the moon, it is the earth orbiting the moon.
>
AFAICT this is the first time you have made this particular claim and
it has nothing to do with either of the claims you made above.
> Try this: Imagine that gravity does not work the way we
>> know it does, or perhaps imagine a massless Earth. So the CG
>> coresponds to the centre of the sun. How would the path of the sun
>> through the ecliptic change from what we presently see?
>
>This is too tricky a dynamics problem. If the earth became massless,
>for example, it would fly off into space (no more attraction from the
>sun).
No, that would be because it gas to travel at c, much too fast to
orbit the sun at this distance.
If you gradually reduced the mass of the earth, its orbit around
>the sun would change, which would affect the cycle time of the path of
>the sun through the ecliptic.
How would the orbit of the earth around the sun change if it only
weighed, say, 1 gm.?
How would the apparant motion of the sun through the ecliptic change?
Remove the moon and place a negligible mass abserver at its location
with its orbital velocity. How would the observations of the appearant
movement of the earth be different?
dkomo
Keep in mind what the original post was for this entire thread:
----------------------------------------------------------------------
Which of the four objects listed below orbits Earth?
1) Moon
2) Sun
3) Mars
4) Venus
----------------------------------------------------------------------
To which I replied in jest, on 1/5/2007:
----------------------------------------------------------------------
Heh. I'll take all of the above. It depends on what you use as a
reference point. If you stand st the center of gravity, then the earth
and moon both orbit around you. But...
If you stand on the moon, the earth appears to orbit the moon. And...
If you stand on the earth, the moon, sun, mars and venus, as well as all
the stars in the heavens appear to orbit the earth, as the ancient
astronomers discovered.
----------------------------------------------------------------------
Even though it was in jest, it is nonetheless true. This is after all,
the principle of relative motion. How you perceive things moving
depends on your reference point. The ancient astronomers assumed the
earth was fixed, and that eventually led to the whole complicated system
of Ptolemaic astronomy.
So this is my *main* and original "claim": If you stand on the moon, the
earth appears to orbit the moon.
To which riplin piped up with, on 1/6/2007:
-----------------------------------------------------------------------
No it doesn't, it remains stationary (but rotating) at a fixed point in
the sky.
-----------------------------------------------------------------------
Well, he's flat out wrong with that statement. The earth will appear to
drift relative to the fixed stars in a 28 day cycle. Its apparent
orbital motion is therefore detectable. Just as the sun's apparent
orbital motion against the stars in a cycle lasting a year is detectable.
Then he said in a recent post that it's really the stars that appear to
move past the earth. And I replied in today's post that it doesn't
frackin' matter which view you take: earth moving past the stars or
stars moving past the earth. It's just a matter of which reference
point you choose.
>
>> Try this: Imagine that gravity does not work the way we
>>
>>>know it does, or perhaps imagine a massless Earth. So the CG
>>>coresponds to the centre of the sun. How would the path of the sun
>>>through the ecliptic change from what we presently see?
>>
>>This is too tricky a dynamics problem. If the earth became massless,
>>for example, it would fly off into space (no more attraction from the
>>sun).
>
>
> No, that would be because it gas to travel at c, much too fast to
> orbit the sun at this distance.
>
> If you gradually reduced the mass of the earth, its orbit around
>
>>the sun would change, which would affect the cycle time of the path of
>>the sun through the ecliptic.
>
>
> How would the orbit of the earth around the sun change if it only
> weighed, say, 1 gm.?
> How would the apparant motion of the sun through the ecliptic change?
>
> Remove the moon and place a negligible mass abserver at its location
> with its orbital velocity. How would the observations of the appearant
> movement of the earth be different?
>
This is leading into complications that seem irrelevant. Enough of
these attempts at Socratic dialog. The whole discussion with riplin is
already surreal enough.
Do you or do you not agree with riplin that the earth's apparent orbital
motion would not be detectable from the moon? A simple yes or no will
suffice.
rip...@azonic.co.nz
dkomo wrote:
> > ----------------Your first claim----------------
> >
> >
> >>>>>>>>>"Jitter" was an imprecise word to use. What actually happens is that
> >>>>>>>>>the earth's center of gravity traces out a small elliptical orbit around
> >>>>>>>>>the center of gravity of the earth-moon system. Standing on the moon,
> >>>>>>>>>you should be able to detect this motion with the right instruments.
> >
> >
> > -----------------------------------------------------
> >
> >>>>>>>Further to that, if you were somewhere other than the moon and was in a
> >>>>>>>fixed position relative to the earth (eg orbitting the sun at the same
> >>>>>>>rate as the earth) then you would be able to detect the earth orbitting
> >>>>>>>the common CoG with the moon by it being displaced 'sideways' several
> >>>>>>>1000km on a 28 day cycle. But you cannot detect that from the moon
> >>>>>>>because the displacement is always exactly away from the moon.
> >>>>>>
> > -------------Your second claim--------------
> >
> >
> >>>>>>What you are saying is absurd.
> >>>>>
> > -----------------------------------------------------
> Keep in mind what the original post was for this entire thread:
You made a claim that what I said was 'absurd'.
> Even though it was in jest, it is nonetheless true. This is after all,
> the principle of relative motion. How you perceive things moving
> depends on your reference point. The ancient astronomers assumed the
> earth was fixed, and that eventually led to the whole complicated system
> of Ptolemaic astronomy.
That may be true, but you are so obsessed with 'relative motion' that
you extend it to areas where it is simply _not_ true.
> So this is my *main* and original "claim": If you stand on the moon, the
> earth appears to orbit the moon.
And that is simply not true. When standing on the Moon the Earth does
_not_ 'appear to orbit the Moon'. It appears to stand still in the sky.
The stars and Sun may appear to orbit the moon.
If it were to 'appear to orbit the moon' then it would set behind one
horizon and rise from another.
If you were standing _above_ the North Pole of the Moon and facing a
particular star _then_ the Earth would appear to orbit you, it would go
behind you on one side and appear on the other, and the Moon would
revolve beneath your feet.
But from the frame of reference of "standing on the Moon" the Earth
would not appear to move at all.
> To which riplin piped up with, on 1/6/2007:
>
> -----------------------------------------------------------------------
> No it doesn't, it remains stationary (but rotating) at a fixed point in
> the sky.
> -----------------------------------------------------------------------
>
> Well, he's flat out wrong with that statement. The earth will appear to
> drift relative to the fixed stars in a 28 day cycle.
No. Wrong. It will remain at a particular angle above the horizon in a
fixed spot and the stars will appear to drift past it.
The _stars_ will appear to set on one horizon and will rise on the
other, the earth never will.
> Its apparent orbital motion is therefore detectable.
Your claim was """that the earth's center of gravity traces out a small
elliptical orbit around the center of gravity of the earth-moon system.
Standing on the moon, you should be able to detect this motion with
the right instruments."""
You are confused. The drift of the stars will _not_ show the 'small
elliptical orbit'. This "orbit around the center of gravity of the
earth-moon system" is not the sames as 'orbitting the moon'.
So regardless of whether you think 'the earth appears to orbit the
moon' this is irrelevant to your claim about the 'small eliptical
orbit' which you said my reply was 'absurd'.
> Just as the sun's apparent
> orbital motion against the stars in a cycle lasting a year is detectable.
You are _very_ confused. You never see the "sun's motion against the
stars" When you can see the Sun the stars are not visible and vice
versa.
Have you ever been outside and looked up ?
> Then he said in a recent post that it's really the stars that appear to
> move past the earth. And I replied in today's post that it doesn't
> frackin' matter which view you take: earth moving past the stars or
> stars moving past the earth. It's just a matter of which reference
> point you choose.
Which has _nothing_ to do with your claim about the 'small eliptical
orbit around the common CoG' or what you said was 'absurd'.
> This is leading into complications that seem irrelevant. Enough of
> these attempts at Socratic dialog. The whole discussion with riplin is
> already surreal enough.
Mainly because you made the claim about the 'small eliptical orbit
around the common CoG' and then fail to address that issue and wander
off into other unrelated orbits.