New mystery planet

Neil Gerace wrote:

and it's supported by four elephants on the back of a giant turtle that
swims around :-)




I'm trying to figure out if this would actually work (not the Discworld,
an actual disc-shaped planet) The idea seems to be to have the planet
rotate at high speed so that it flattens out while at the same time
having its axis of rotation at ninety degree angle to its orbital
direction and being gravitationally locked to the star it's orbiting so
that the flat side of the disc always faces the star as it orbits around
it. This sound awfully strange, as it implies that the planet's orbital
axis got swung through ninety degrees after it formed.
I think Occam's razor favors a low density planet over this idea.

Pat

Jim McCauley wrote:

Yet another Mysterians fan? Of course, when them li'l nasties finally show
up, you're gonna cry 96 tears.


?
Funny, huh?
I got it.
Want to see someone as crazed as I am about that movie?:
http://www.bills-kitchen.com/MarkaliteProgress.html
....and to actually bring this on-topic for the newsgroup, here's his
Gemini-Agena model:
http://www.bills-kitchen.com/gemini.html
Nice movie of Gemini 8 going out of control.
http://www.bills-kitchen.com/gemini/gemini.mov

Pat


Jim McCauley

Pat Flannery wrote:



Neil Gerace wrote:

and it's supported by four elephants on the back of a giant turtle
that swims around :-)




I'm trying to figure out if this would actually work (not the Discworld,
an actual disc-shaped planet) The idea seems to be to have the planet
rotate at high speed so that it flattens out while at the same time
having its axis of rotation at ninety degree angle to its orbital
direction and being gravitationally locked to the star it's orbiting so
that the flat side of the disc always faces the star as it orbits around
it. This sound awfully strange, as it implies that the planet's orbital
axis got swung through ninety degrees after it formed.
I think Occam's razor favors a low density planet over this idea.

Pat


Um, I think ther'd be signifigant physical integrity problems before
you spin it up enough to become more than a very oblate sphereoid. The
details worked up by the late Hal Clement for the fictional planet
'Mesklin' (from 'Mission of Gravity') are a useful guide:

http://en.wikipedia.org/wiki/Mesklin

http://www.strangehorizons.com/2002/.../planets.shtml


But at the imaginable extreme, there's the 'Alderson Disk' (which
admittedly doesn't depend on rotation at all):

http://en.wikipedia.org/wiki/Alderson_disk

http://lists.travellerrpg.com/piperm...ry/019226.html


--

Frank

You know what to remove to reply...

Check out my web page: http://www.geocities.com/stardolphin1/link2.htm

"Man who say it cannot be done, should not interrupt man doing it."
- Chinese Proverb

On Thu, 14 Sep 2006 23:56:52 -0400, Alan Anderson
wrote:

Pat Flannery wrote:

http://www.spaceref.com/news/viewpr.html?pid=20819
So it's far bigger than Jupiter, and far closer to its primary (type G)
than Mercury.
...and yet is incredibly low in density, although you would have thought
its atmosphere would have boiled off eons ago at that distance and heat.

My immediate wild idea is that the mystery planet is more disk-shaped
than spherical, and happens to present its large profile in our
direction. How big and fluffy would Saturn look from another star if it
were in the right orientation?


This might seem incredibly obvious but what happens to gas when you
heat it up? It expands. So if you took say, Jupiter and moved it
close enough to the sun that it's orbit was only 4.5 days it would
receive a LOT of heat and would expand accordingly. How big might it
be once it had reached equilibrium? I'm wondering why they think it's
such a mystery. I'm sure there's some temperature/gravity/diameter
limiit beyond which the atmosphere begins to drift off into space and
is the planet in question beyond that?

NoBody Here wrote:

On Thu, 14 Sep 2006 23:56:52 -0400, Alan Anderson
wrote:


Pat Flannery wrote:


http://www.spaceref.com/news/viewpr.html?pid=20819
So it's far bigger than Jupiter, and far closer to its primary (type G)
than Mercury.
...and yet is incredibly low in density, although you would have thought
its atmosphere would have boiled off eons ago at that distance and heat.

My immediate wild idea is that the mystery planet is more disk-shaped
than spherical, and happens to present its large profile in our
direction. How big and fluffy would Saturn look from another star if it
were in the right orientation?



This might seem incredibly obvious but what happens to gas when you
heat it up? It expands. So if you took say, Jupiter and moved it
close enough to the sun that it's orbit was only 4.5 days it would
receive a LOT of heat and would expand accordingly.

But, I suspect, not by very much. (Though a similar effect, caused
by unexpectly high solar activity, led to the earlier-than expected
demise of Skylab, as the remnants of Earth's atmosphere at its orbital
altitude became slightly denser than normal, increasing drag.)

How big might it
be once it had reached equilibrium? I'm wondering why they think it's
such a mystery. I'm sure there's some temperature/gravity/diameter
limiit beyond which the atmosphere begins to drift off into space and
is the planet in question beyond that?


I don't know about diameter, but the molecular weight of the gases
is a factor, too. Of those gases likely to be in a planetary atmosphere,
hydrogen leaves most easily, CO2 is generally the last to go, all other
things being equal.

--

Frank

You know what to remove to reply...

Check out my web page: http://www.geocities.com/stardolphin1/link2.htm

"Man who say it cannot be done, should not interrupt man doing it."
- Chinese Proverb

This might seem incredibly obvious but what happens to gas when you
heat it up? It expands. So if you took say, Jupiter and moved it
close enough to the sun that it's orbit was only 4.5 days it would
receive a LOT of heat and would expand accordingly. How big might it
be once it had reached equilibrium? I'm wondering why they think it's
such a mystery. I'm sure there's some temperature/gravity/diameter
limiit beyond which the atmosphere begins to drift off into space and
is the planet in question beyond that?

There's a few other transiting planets where the theory that would
predict how much a Jupiter would expand its atmosphere as a hot jupiter
works out right. But the mystery planet is larger than the theory would
predict.

robert casey wrote:

This might seem incredibly obvious but what happens to gas when you
heat it up? It expands. So if you took say, Jupiter and moved it
close enough to the sun that it's orbit was only 4.5 days it would
receive a LOT of heat and would expand accordingly. How big might it
be once it had reached equilibrium? I'm wondering why they think it's
such a mystery. I'm sure there's some temperature/gravity/diameter
limiit beyond which the atmosphere begins to drift off into space and
is the planet in question beyond that?

There's a few other transiting planets where the theory that would
predict how much a Jupiter would expand its atmosphere as a hot jupiter
works out right. But the mystery planet is larger than the theory would
predict.

If it really doesn't have a solid core of heavier elements then that
also means that similar planets might have formed around stars much
earlier than planet formation was though possible before.

Pat Flannery wrote:

http://www.spaceref.com/news/viewpr.html?pid=20819
So it's far bigger than Jupiter, and far closer to its primary (type G)
than Mercury.
...and yet is incredibly low in density, although you would have thought
its atmosphere would have boiled off eons ago at that distance and heat.

Maybe the mystery planet is really a pair of jupiters in a tight orbit
with each other (binary jupiter)? Thus you could have more starlight
blockage for the total mass involved? Can you create a pair of planets
like that, and successfully migrate the pair to become hot jupiters, and
keep them together close to the star?

In sci.space.policy, on Mon, 18 Sep 2006 01:03:16 GMT,
robert casey sez:

` Pat Flannery wrote:

` http://www.spaceref.com/news/viewpr.html?pid=20819
` So it's far bigger than Jupiter, and far closer to its primary (type G)
` than Mercury.
` ...and yet is incredibly low in density, although you would have thought
` its atmosphere would have boiled off eons ago at that distance and heat.

` Maybe the mystery planet is really a pair of jupiters in a tight orbit
` with each other (binary jupiter)? Thus you could have more starlight
` blockage for the total mass involved? Can you create a pair of planets
` like that, and successfully migrate the pair to become hot jupiters, and
` keep them together close to the star?

Perhaps there are other mechanisms for close orbiting planets to occlude
sunlight. What if it were trailing a large gas plume like a comet?
How long might it be expected to be capable of doing that, compared
to the lifetime of the star?

--
================================================== ========================
Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

pete wrote:

Perhaps there are other mechanisms for close orbiting planets to occlude
sunlight. What if it were trailing a large gas plume like a comet?
How long might it be expected to be capable of doing that, compared
to the lifetime of the star?



Well Beta Lyra has a companion smaller star that circles it every 13
days and has developed a accretion torus from gas of its primary being
swept up by it:
http://es.geocities.com/gas_astronom...etaLyra_i4.gif
http://www.vor.ru/Space_now/Artists/24b.jpg
Given this planet's closer orbit, is something like that going on here also?
Is the planet absorbing the star's solar wind and gases from its
prominences and growing as a result?
Is the reason it's so light that its atmosphere is made up of extremely
hot captured hydrogen and helium?

Pat