What kind of self-respecting planet has a moon 1/2 its diameter?

On Fri, 17 Jul 2015 07:58:40 -0700 (PDT), Quadibloc
wrote:

Given that in some sense the "real" definition of "planet" is "one of the big,
important objects in the Solar System to which we pay attention because there
aren't very many of them", and it is _because_ that's the real definition that
it was OK to have Ceres, Vesta, Pallas, and Juno as four additional planets in
the Solar System... but when a large bunch of other asteroids started to be
discovered (including many larger than Vesta) then the asteroids had to be
dropped, then that Pluto got dropped as a planet because the alternative was
Eris and Sedna and dozens of other Kuiper Belt objects being acknowledged as
planets too.

So the idea is that one draws the line at including objects as planets wherever
the line needs to be drawn not to have hundreds or thousands of them.

In practice, at conferences and in discussion, I find that no line is
really drawn. Most astronomers continue to use "planet" in its most
casual sense, and largely ignore the IAU definition. So a "planet" is
whatever it needs to be to make a point clear. I hear larger asteroids
called planets all the time. I hear KBOs called planets all the time.
Most people seem to consider any spherical body orbiting the Sun a
planet, and then simply qualify that term as needed (dwarf,
terrestrial, gas giant).

In my own area of space dust research, we consider the dynamics of
stellar system formation, and what we call planets is quite different
from the IAU definition. We haven't stopped using "planet" or tried to
come up with another word.

The IAU definition is observed more formally in papers (as we'd
expect). But it's clear that few have rigorously adopted that
nomenclature outside of publication.

These mindless thugs went out of their way to 'define' a planet when the conception of a planet is ancient and are termed by their observed motions against the background field of distant stars as opposed to the direct motions of the moon and the Sun .

" Moreover, we see the other five planets also retrograde at times, and stationary at either end [of the regression]. And whereas the sun always advances along its own direct path, they wander in various ways, straying sometimes to the south and sometimes to the north; that is why they are called "planets" [wanderers]. " Copernicus


The 21st century innovation is accounting for two separate ways the planets wander against the background stars using perspectives which are based on the motion and position of the Earth.

All the recent 'definition' did was show how intellectually weak these academics are in the face of genuine astronomy.



Because they are thugs they lost control of the arguments and now want everyone to believe they understand the wreckage they have created.

On Friday, July 17, 2015 at 9:22:40 AM UTC-6, Chris L Peterson wrote:

In practice, at conferences and in discussion, I find that no line is
really drawn. Most astronomers continue to use "planet" in its most
casual sense, and largely ignore the IAU definition. So a "planet" is
whatever it needs to be to make a point clear. I hear larger asteroids
called planets all the time. I hear KBOs called planets all the time.

Well, I'm not surprised. You astronomy guys will call carbon or even oxygen a
"metal"! (That is, astrophysicists, when dealing with the elements of the
interstellar medium, or within stars, call everything after helium a metal.
Well, they *start out* right, since lithum is indeed a metal, an alkali metal,
in fact.)

John Savard

On Fri, 17 Jul 2015 11:13:16 -0700 (PDT), Quadibloc
wrote:

On Friday, July 17, 2015 at 9:22:40 AM UTC-6, Chris L Peterson wrote:

In practice, at conferences and in discussion, I find that no line is
really drawn. Most astronomers continue to use "planet" in its most
casual sense, and largely ignore the IAU definition. So a "planet" is
whatever it needs to be to make a point clear. I hear larger asteroids
called planets all the time. I hear KBOs called planets all the time.

Well, I'm not surprised. You astronomy guys will call carbon or even oxygen a
"metal"! (That is, astrophysicists, when dealing with the elements of the
interstellar medium, or within stars, call everything after helium a metal.
Well, they *start out* right, since lithum is indeed a metal, an alkali metal,
in fact.)

True enough!

On Thursday, July 16, 2015 at 9:07:08 PM UTC-4, Chris L Peterson wrote:
On Thu, 16 Jul 2015 17:31:34 -0700 (PDT), wsnell01 wrote:

Where would you like to draw the line?

In the professional world, this is a matter of ongoing discussion,
given that the definition of "planet" is still evolving.

Charon is not in orbit around Pluto, but around the Sun. The two
bodies have a barycenter outside of both. By some provisional
definitions, and certainly by some definitions in informal use, both
are planets, and as such would be considered a binary planetary
system.

This is similar to the Earth-Moon system. The Moon isn't in orbit
around the Earth, and it is spherical. So it could be considered to
have planet status. But as long as the Earth-Moon barycenter remains
inside the Earth, the Moon is likely to remain categorized as a moon.
In a few billion years, the barycenter will be above Earth's surface,
and this system might be treated as a binary planet. Not that there's
likely to be any intelligent species around to make that judgment.

This talk of "barycenters" is sophistry, peterson. The density of the larger body would have to be considered, but you're just ignoring that.

If the Sun could suddenly cease to exist, the Moon would still orbit the Earth, Charon would still orbit the planet Pluto.

On Mon, 20 Jul 2015 09:17:00 -0700 (PDT), wrote:

This is similar to the Earth-Moon system. The Moon isn't in orbit
around the Earth, and it is spherical. So it could be considered to
have planet status. But as long as the Earth-Moon barycenter remains
inside the Earth, the Moon is likely to remain categorized as a moon.
In a few billion years, the barycenter will be above Earth's surface,
and this system might be treated as a binary planet. Not that there's
likely to be any intelligent species around to make that judgment.

This talk of "barycenters" is sophistry, peterson. The density of the larger body would have to be considered, but you're just ignoring that.

The location of the barycenter is fundamental to considering whether
most objects are treated as parent-moon systems or binary object
systems. I've never seen density considered.

If the Sun could suddenly cease to exist, the Moon would still orbit the Earth, Charon would still orbit the planet Pluto.

Which has nothing to do with my observation that these moons are in
primary orbit around the Sun.

Once again, you choose to sabotage a reasonable scientific discussion
out of nothing more than a need to pointlessly argue.

On Monday, July 20, 2015 at 1:04:21 PM UTC-4, Chris L Peterson wrote:
On Mon, 20 Jul 2015 09:17:00 -0700 (PDT), wsnell01 wrote:

This is similar to the Earth-Moon system. The Moon isn't in orbit
around the Earth, and it is spherical. So it could be considered to
have planet status. But as long as the Earth-Moon barycenter remains
inside the Earth, the Moon is likely to remain categorized as a moon.
In a few billion years, the barycenter will be above Earth's surface,
and this system might be treated as a binary planet. Not that there's
likely to be any intelligent species around to make that judgment.

This talk of "barycenters" is sophistry, peterson. The density of the larger body would have to be considered, but you're just ignoring that.

The location of the barycenter is fundamental to considering whether
most objects are treated as parent-moon systems or binary object
systems. I've never seen density considered.

That's a flaw in your concept.

If the Sun could suddenly cease to exist, the Moon would still orbit the Earth, Charon would still orbit the planet Pluto.

Which has nothing to do with my observation that these moons are in
primary orbit around the Sun.

You haven't used the term "primary orbit" previously in this thread.

Once again, you choose to sabotage a reasonable scientific discussion
out of nothing more than a need to pointlessly argue.

Were you to stick to scientific and/or logical discussions, there would be no need to call you out, peterson.

On Mon, 20 Jul 2015 10:31:53 -0700 (PDT), wrote:

The location of the barycenter is fundamental to considering whether
most objects are treated as parent-moon systems or binary object
systems. I've never seen density considered.

That's a flaw in your concept.

It's not my concept. It's simply a statement of how the professional
astronomical community has chosen to define things.

On Monday, July 20, 2015 at 1:57:42 PM UTC-4, Chris L Peterson wrote:
On Mon, 20 Jul 2015 10:31:53 -0700 (PDT), wsnell01 wrote:

The location of the barycenter is fundamental to considering whether
most objects are treated as parent-moon systems or binary object
systems. I've never seen density considered.

That's a flaw in your concept.

It's not my concept. It's simply a statement of how the professional
astronomical community has chosen to define things.

Are the following your words or those of the professional astronomical cummunity?:

" Charon is not in orbit around Pluto, but around the Sun. The two
bodies have a barycenter outside of both. By some provisional
definitions, and certainly by some definitions in informal use, both
are planets, and as such would be considered a binary planetary
system."

" This is similar to the Earth-Moon system. The Moon isn't in orbit
around the Earth, and it is spherical. So it could be considered to
have planet status. But as long as the Earth-Moon barycenter remains
inside the Earth, the Moon is likely to remain categorized as a moon.
In a few billion years, the barycenter will be above Earth's surface,
and this system might be treated as a binary planet. Not that there's
likely to be any intelligent species around to make that judgment."

On Mon, 20 Jul 2015 11:41:02 -0700 (PDT), wrote:

Are the following your words or those of the professional astronomical cummunity?:

" Charon is not in orbit around Pluto, but around the Sun. The two
bodies have a barycenter outside of both. By some provisional
definitions, and certainly by some definitions in informal use, both
are planets, and as such would be considered a binary planetary
system."

This is the view of the professional community.

" This is similar to the Earth-Moon system. The Moon isn't in orbit
around the Earth, and it is spherical. So it could be considered to
have planet status. But as long as the Earth-Moon barycenter remains
inside the Earth, the Moon is likely to remain categorized as a moon.
In a few billion years, the barycenter will be above Earth's surface,
and this system might be treated as a binary planet. Not that there's
likely to be any intelligent species around to make that judgment."

This is the view of the professional community.