Earth2 ?

If there were another planet, same mass as Earth and in the same orbit but
at the precise opposite orbital position, we would presumably never see it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins

"Jim Hawkins" wrote in message
m...
If there were another planet, same mass as Earth and in the same orbit but
at the precise opposite orbital position, we would presumably never see it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins


It would be detectable due to its perturbation of the orbits of other solar
system objects.

"OG" wrote in message
...

"Jim Hawkins" wrote in message
m...
If there were another planet, same mass as Earth and in the same orbit
but
at the precise opposite orbital position, we would presumably never see
it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins


It would be detectable due to its perturbation of the orbits of other
solar system objects.


Yes.

And perturbations by other planets would move it out from behind the sun
where it could be seen, and from time to time it would approach the
longitude of the Earth, when all hell would break loose due to tides while
the two passed each other. The situation would resemble the co-orbital
moons of Saturn, Janus and Epimetheus.

Even the "presumably" of the OP is wrong. At total eclipses of the Sun, any
Earth-similar planet on the opposite side of the Sun would be directly
visible more times than not. The Earth's orbit isn't circular and Kepler's
second law would apply, so it would not always be exactly 180 deg different
in true anomaly.

Objects like Cruithne (which has the same period as Earth) could not exist
in a captured orbit if an Earth-like planet had a similar orbit. This goes
back to OG's point, of course.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

"Mike Dworetsky" wrote in message
...
"OG" wrote in message
...

"Jim Hawkins" wrote in message
m...
If there were another planet, same mass as Earth and in the same orbit
but
at the precise opposite orbital position, we would presumably never see
it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins


It would be detectable due to its perturbation of the orbits of other
solar system objects.


Yes.

And perturbations by other planets would move it out from behind the sun
where it could be seen, and from time to time it would approach the
longitude of the Earth, when all hell would break loose due to tides while
the two passed each other. The situation would resemble the co-orbital
moons of Saturn, Janus and Epimetheus.

Even the "presumably" of the OP is wrong. At total eclipses of the Sun,
any Earth-similar planet on the opposite side of the Sun would be directly
visible more times than not. The Earth's orbit isn't circular and
Kepler's second law would apply, so it would not always be exactly 180 deg
different in true anomaly.

Objects like Cruithne (which has the same period as Earth) could not exist
in a captured orbit if an Earth-like planet had a similar orbit. This
goes back to OG's point, of course.

--
Mike Dworetsky


Thanks for the explanations, Mike and OG (and thanks to A N Other who sent
me an email on the same lines).

Jim Hawkins

In uk.sci.astronomy message dNednQy4CJfjqcjVnZ2dneKdnZydnZ2d@supernews.
com, Sun, 15 Jun 2008 16:25:46, Jim Hawkins
posted:
If there were another planet, same mass as Earth and in the same orbit but
at the precise opposite orbital position, we would presumably never see it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?


Even if the Universe consisted solely of the Sun, Earth in circular
orbit, and counter-Earth, the system would not be dynamically stable; it
would be like an infinitely-sharp pencil balanced on its point in an
infinitely-hard flat surface. That conclusion is independent of the
mass of counter-Earth.

Plus what others have said.

The argument that the Earth's orbit is not circular, and hence its
angular velocity is not constant, implies that a body in the same
orbital path would not remain diametrically opposite. But a body in an
orbit of the same shape but "pointing" in the opposite direction to
ours, if initially behind the Sun, would remain so until the effects of
perturbations and instability accrued. That's analogous to L4 & L5
still working for elliptical orbits.

--
(c) John Stockton, nr London, UK. Turnpike v6.05 MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

On Jun 16, 12:24*am, "Jim Hawkins" wrote:
"Mike Dworetsky" wrote in message

...





"OG" wrote in message
...

"Jim Hawkins" wrote in message
news:dNednQy4CJfjqcjVnZ2dneKdnZydnZ2d@supernews. com...
If there were another planet, same mass as Earth and in the same orbit
but
at the precise opposite orbital position, we would presumably never see
it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins

It would be detectable due to its perturbation of the orbits of other
solar system objects.

Yes.

And perturbations by other planets would move it out from behind the sun
where it could be seen, and from time to time it would approach the
longitude of the Earth, when all hell would break loose due to tides while
the two passed each other. *The situation would resemble the co-orbital
moons of Saturn, Janus and Epimetheus.

Even the "presumably" of the OP is wrong. *At total eclipses of the Sun,
any Earth-similar planet on the opposite side of the Sun would be directly
visible more times than not. *The Earth's orbit isn't circular and
Kepler's second law would apply, so it would not always be exactly 180 deg
different in true anomaly.

Objects like Cruithne (which has the same period as Earth) could not exist
in a captured orbit if an Earth-like planet had a similar orbit. *This
goes back to OG's point, of course.

--
Mike Dworetsky

Thanks for the explanations, Mike and OG (and thanks to A N Other who sent
me an email on the same lines).

Jim Hawkins- Hide quoted text -

- Show quoted text -



The only thing that is perturbed are these guys and their thinking for
while they talk of an elliptical orbital geometry,the framework they
use is circular -

http://upload.wikimedia.org/wikipedi...3%A9reo.en.png

Your hypothetical question aside,the ability to believe that you can
reference axial rotation off celestial sphere geometry while
referencing orbital motion off the central Sun is truly a remarkable
belief in a simpleminded sort of way,the genuine belief among
empiricists that they actually can justify axial rotation in 23 hours
56 minutes 04 seconds because they can see a star returning back to a
observed location in that time.Aaarrr, Jim lad,were it only that
simple.

If the anonymous science entity thinks it can script whatever
explanation it wants and sell it to the general population then they
should learn that the trick of obfuscation,no matter how elaborate and
supported,does not work. In this respect,there is some joy this week
in seeing ordinary people reject a European treaty even though the
treaty had the backing of every organisation with power,a re-packaged
treaty that was given a new name and wrapped up in legalise in order
to bludgeon people into acceptance,the same tactic used in a section
of science day in and day out.Only this time it failed.

Given a chance,people do find their voice,the dismay of politicians in
seeing that people will not follow something because they are told it
is good for them is outweighed by the sense that originality and the
tendency to fight against mediocrity and bureocracy is not quite dead
yet.Oh that it existed in these forums where even those who towed an
anonymous empirical line realised the damage that was and is still
being done using terrestrial/celestial phenomena.

On 17 Jun, 05:16, oriel36 wrote:
the genuine belief among
empiricists that they actually can justify axial rotation in 23 hours
56 minutes 04 seconds because they can see a star returning back to a
observed location in that time.Aaarrr, Jim lad,were it only that
simple.


Of course it could be that you are correct and thousands of
professional and amateur astronomers are wrong.

However until you can be bothered to publish a detailed explanation of
your theories in a peer reviewed journal I am inclined to believe the
majority.

However until you can be bothered to publish a detailed explanation of
your theories in a peer reviewed journal I am inclined to believe the
majority.

Hey, DC Comics have known about Earth2 since the 60s, at least. Could
thousands of comic book readers have been misled?

On Jun 18, 10:07*am, wrote:
On 17 Jun, 05:16, oriel36 wrote:

the genuine belief among
empiricists that they actually can justify axial rotation in 23 hours
56 minutes 04 seconds because they can see a star returning back to a
observed location in that time.Aaarrr, Jim lad,were it only that
simple.

Of course it could be that you are correct and thousands of
professional and amateur astronomers are wrong.


Here is a case of so-called irreducable complexity,remove or alter any
part of the 'sidereal time' justification and the whoile thing
disintegrates -

http://upload.wikimedia.org/wikipedi...3%A9reo.en.png

Pick whatever one you like - The natural noon cycle is not 24 hours
exactly for one,there is no constant orbital motion for another but by
then it becomes a matter of demonstrating that the 'sidereal
framework' is a bogus construction and hardly the thinking of
reasonable individuals

I have moved away from opposing people who really want the Earth to
rotate through 360 degrees in 23 hours 56 minutes 04 seconds just as I
would have little to say to others who wish to believe the Earth was
created in 7 days,as far as I am concerned such people are welcome to
their beliefs and I would be wrong to disturb their elaborate
conceptual constructions.




However until you can be bothered to publish a detailed explanation of
your theories in a peer reviewed journal I am inclined to believe the
majority.

Offer that poison chalice,no thanks,that is probably at the core of
problem and I am less inclined to criticise that process than I am
those who cannot alter their views to more stable and enjoyable
constructs such as how the 24 hour day is created out of variations in
the natural noon cycle,modifying the explanation for the seasons,apply
rotational dynamics to geological crustal dynamics,things like that.

The peer review process probably started Iin earnest after Newton
while the error created by Flamsteed in drawing a false conclusion
existed before the emergence of the empirical approach to astronomy
and subsequently with the peer review process in tow.Without the
slightest trace of grandstanding or ego,I am qualified to 'peer
review' Flamsteed's asserted proof for constant axial rotation and
find it unsatisfactory.I have demonstrated exactly where it is wrong
and if nobody can act on the information then obviously it will
refllect back into the standard of contemporary peer review.

As you can see,something happened within the past few years for a
fatigue to set in,an ennui that cannot be removed by any amount of
novelties that come under the name of astronomy,even genuine technical
achievements such as the Mars lander cannot generate anything beyond a
brief flash to humanity who have become too accustomed to these
things.The reference to the Lisbon treaty is not out of context,the
wishes of the political world are not those of people who live their
lives withiin the context of Europe,their country,their town,their
homes and finally themselves.My astronomy begins with the individual
and the power of the individual to rise to the appreciation of
terrestrial/celestial phenomena,not as part of some ideological
bandwagon but as a free person who acknowledges how our existence is
so wrapped up in the celestial arena and how our bodies respond to the
daily and annual cycles of the Earth.

A good start would be to appreciate how clocks are kept in sync with
the daily cycle at 24 hours/360 degrees.

On Jun 16, 10:16 pm, oriel36 wrote:

Your hypothetical question aside,the ability to believe that you can
reference axial rotation off celestial sphere geometry while
referencing orbital motion off the central Sun

Nah. Celestial sphere geometry is just a convenience for knowing where
to point things. If you're going to do any calculating, there's only
one geometry to use - Cartesian coordinates, x, y, and z.

Unless, of course, general relativistic effects are so strong that
they're nonlinear; then there's nothing for it but to go whole hog
with tensor calculus. Thankfully, while general relativistic effects
are strong enough to be *detectable* in the precession of Mercury,
they're still nowhere near strong enough to require THAT. (Depending
on the precision you need, of course.)

is truly a remarkable
belief in a simpleminded sort of way,the genuine belief among
empiricists that they actually can justify axial rotation in 23 hours
56 minutes 04 seconds because they can see a star returning back to a
observed location in that time.

Well, we have to start with the simple stuff.

Aaarrr, Jim lad, were it only that
simple.

Celestial motions *are* a whole lot simpler if you can untangle them,
and look at one motion at a time. Using the distant stars as an
approximation to a stationary coordinate system _is_ a great way to
get started. If you don't like it - that's your problem, not ours, I'm
afraid.

In this respect, there is some joy this week
in seeing ordinary people reject a European treaty even though the
treaty had the backing of every organisation with power,

Here's something I agree with you about. Most Europeans don't want a
less-responsive European Parliament and are happy with their own
national governments. However, with a free trade area, a common
currency - the Euro - _is_ needed to gain the full benefits, so a case
can be made for some additional integration over and above that of the
original European Economic Community.

And from what I've heard about the issue, you are also right that the
new treaty is much the same as the old one that was rejected in
referendums despite it being claimed that it is different enough so
that no referendums are appropriate this time.

But modern science is hard to understand *not* because scientists have
dressed it up in jargon, but because it genuinely *depends* on fancy
mathematics.

Oh that it existed in these forums where even those who towed an
anonymous empirical line realised the damage that was and is still
being done using terrestrial/celestial phenomena.

I can't even guess what damage you are referring to that we were aware
of. I wish I could usefully communicate with you to get information
about where we're supposed to be wrong that I could get a grip on.

John Savard