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Is Amalthea considered a minor moon?

Posted: 16.04.2008, 13:38
by cartrite
cartrite wrote:Does the file numberedmoons.ssc contain all minormoons?
cartrite

ElChristou wrote:Don't think so; the file named minormoons.ssc must define a few others... or not? (if not the name is not very appropriate... :?)

They look like they were all minor moons. Not all of them had numbers though. Some had names and there is a ton of them. Jupiter for example, only the 5 moon labels, Amalthea, Io, Euproa, Ganymede, and Callisto are displayed when I type "m". The ones in solarsys.ssc. When I type "M" or "shift + m" all the others are displayed as well. And there are a lot of them. Is Amalthea considered a minor moon?

I moved this in case it starts something.
cartrite

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 14:04
by ajtribick
I would suggest that "major" moons should be the ones that are (roughly) spherical, i.e.:

Around Earth: The moon
Around Jupiter: Io, Europa, Ganymede, Callisto
Around Saturn: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Iapetus
Around Uranus: Miranda, Ariel, Umbriel, Titania, Oberon
Around Neptune: Triton
Around Pluto: Charon

All others should be minor moons.

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 14:17
by ElChristou
The problem is that phobos and deimos are considered (at least in the public mind) as moons of Mars...

For Jupiter, the inner group is well defined what about making them moons and the rest minor moons? (Galileans + Metis, Adrastea, Thebe and Almathea)

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 14:34
by ajtribick
Yeah, I was expecting someone to point out Phobos and Deimos. Maybe given the absence of large satellites these should get the major moon treatment.

As for the inner group of Jovian moons, I strongly disagree that they should get "major moon" status. There is a clear distinction between the massive Galileans and the inner group which (if Amalthea is anything to go by) are rubble piles.

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 15:22
by ElChristou
I feel the problem is that all bodies discovered before the spacial exploration are already too much in the public mind... For Saturn for example, Janus, Phoebe and Hyperion are quite known as moons of Saturn, no? That's sounds a bit stupid I know... but...

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 15:33
by chris
ajtribick wrote:Yeah, I was expecting someone to point out Phobos and Deimos. Maybe given the absence of large satellites these should get the major moon treatment.

Yes, I think so too.

As for the inner group of Jovian moons, I strongly disagree that they should get "major moon" status. There is a clear distinction between the massive Galileans and the inner group which (if Amalthea is anything to go by) are rubble piles.

Agreed, they get minor moon status.

Other moons that I was thinking about leaving as major moons are Hyperion, Phoebe, Proteus, and Nereid. This is based on a rough (and subjective, I admit) observation that these objects are unique in the regions that they orbit.

Even though Phoebe is in a retrograde orbit, it's much more massive than any of the other satellites out past Iapetus. Same for Nereid: not a retrograde orbiter, but more massive by a factor of > 100 than any other outer moon of Neptune. Proteus is interesting in that it's larger than Mimas, yet distinctly non-spherical.

--Chris

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 16:02
by cartrite
chris wrote:
ajtribick wrote:Yeah, I was expecting someone to point out Phobos and Deimos. Maybe given the absence of large satellites these should get the major moon treatment.

Yes, I think so too.

As for the inner group of Jovian moons, I strongly disagree that they should get "major moon" status. There is a clear distinction between the massive Galileans and the inner group which (if Amalthea is anything to go by) are rubble piles.

Agreed, they get minor moon status.

Other moons that I was thinking about leaving as major moons are Hyperion, Phoebe, Proteus, and Nereid. This is based on a rough (and subjective, I admit) observation that these objects are unique in the regions that they orbit.

Even though Phoebe is in a retrograde orbit, it's much more massive than any of the other satellites out past Iapetus. Same for Nereid: not a retrograde orbiter, but more massive by a factor of > 100 than any other outer moon of Neptune. Proteus is interesting in that it's larger than Mimas, yet distinctly non-spherical.

--Chris
I agree with this. I'm not sure about Pluto though.

Is it save to say that all the moons listed in numberedmoons.ssc are all minor?

Just from a view oriented opinion, Phobos and Deimos are fine as major moons, there are no other moons to clutter up the view when labels are enabled. Before the minormoon class was added, it looked like a cloud of labels around Jupiter when moon labels were enabled.
cartrite

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 17:22
by volcanopele
I guess it depends on the context and situation. I guess for most people, Amalthea is a "minor moon", and will configure it that way in minormoons.ssc. In my own setup, all moons orbiting in their parent's equatorial plane or are larger than 200 km across will be considered major moons, and all others would be labeled minor moons. This is simply to ensure that moons would be imaged by an orbiting spacecraft would show up the same. Plus, these moons don't clutter the screen nearly as much as the outer cloud of moons.

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 17:40
by cartrite
volcanopele wrote:I guess it depends on the context and situation. I guess for most people, Amalthea is a "minor moon", and will configure it that way in minormoons.ssc.
Amalthea is not in minormoons.ssc. At least I don't think it is. It is in solarsys.ssc which is why I asked he question. It is right after the entry for Jupiter. I guess it could be added to the minormoons.ssc and taken out of solarsys.ssc if it is to be considered a minor moon.
cartrite

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 19:09
by BobHegwood
Isn't all of this much ado about nothing? :wink:

I mean, who really cares whether Pluto is considered a dwarf planet, an asteroid, or a rogue moon?

I'm one of the old Geezers who still believes that Pluto is a planet, but I really do NOT care if it's decided
to make it a dwarf planet or an asteroid. You know?

Seems that there are much more important issues at hand. Whether minormoons.ssc is going to cause
problems or not is the least of them. We are probably all going to change its contents anyway.
Who cares? :roll:

I know that I always set up Celestia's files so that I am happy with the way things are displayed. The
remarkable thing about this beautiful system is that it has been designed so that we CAN do that.

Just FYI. Thanks, Brain-Dead

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 19:13
by ajtribick
BobHegwood wrote:Isn't all of this much ado about nothing? :wink:

I mean, who really cares whether Pluto is considered a dwarf planet, an asteroid, or a rogue moon?

I'm one of the old Geezers who still believes that Pluto is a planet, but I really do NOT care if it's decided
to make it a dwarf planet or an asteroid. You know?

Seems that there are much more important issues at hand. Whether minormoons.ssc is going to cause
problems or not is the least of them. We are probably all going to change its contents anyway.
Who cares? :roll:

I know that I always set up Celestia's files so that I am happy with the way things are displayed. The
remarkable thing about this beautiful system is that it has been designed so that we CAN do that.

Just FYI. Thanks, Brain-Dead

I think you've missed the point here. The idea of this "minor moons" thing is to provide a rendering of satellite systems that doesn't clog the display with tonnes of orbits. Sure you can tweak it and all that, but there do have to be default settings, and that's what the discussion is about.

Re: Is Amalthea considered a minor moon?

Posted: 16.04.2008, 19:16
by BobHegwood
ajtribick wrote:
I think you've missed the point here. The idea of this "minor moons" thing is to provide a rendering of satellite systems that doesn't clog the display with tonnes of orbits. Sure you can tweak it and all that, but there do have to be default settings, and that's what the discussion is about.

Okay, maybe I did miss the point, but I still think that it ain't that big a deal. Celestia is almost fully customizable by even us Brain-Dead types. :wink:

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 02:18
by Kolano
Without a strict definition/guidelines of what classifies something as a minor moon vs a moon, disagreements over which is which seem inevitable. If it's something particular to Celestia, I think even a strict definition will be prone to constant attack. Since the only guidance provided thus far seems to be "enough to not not clutter the display" maybe an alternate method of setting moon v minor moons could resolve this.

Could we simply have a config file setting, or in program slider to set something like one of the following parameters?

  • "Max size of minor moon", which would designate a minor moon by it's absolute size.
  • "Max % of minor moon vs planet", which would designate a minor moon by it's size as a percentage of planet size.
  • "Max non-minor moons per planet", which would designate the X largest moons in a planetary system as non-minor.
I'm personally leaning toward the last of those ("Max non-minor moons per planet"), since it seems most likely to consistently resolve the clutter issue. Though perhaps there is a good reasons to select one of the others or a better general algorithm.

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 10:45
by ajtribick
chris wrote:Other moons that I was thinking about leaving as major moons are Hyperion, Phoebe, Proteus, and Nereid. This is based on a rough (and subjective, I admit) observation that these objects are unique in the regions that they orbit.

Even though Phoebe is in a retrograde orbit, it's much more massive than any of the other satellites out past Iapetus. Same for Nereid: not a retrograde orbiter, but more massive by a factor of > 100 than any other outer moon of Neptune. Proteus is interesting in that it's larger than Mimas, yet distinctly non-spherical.

--Chris

Perhaps we should include the largest members of the other satellite groups, to give an idea of the system structure without clogging the display too much.

Jupiter
Inner: Amalthea, Thebe?
Himalia group: Himalia, Elara, Lysithea?
Ananke group: Ananke
Carme group: Carme
Pasipha? group: Pasipha?, Sinope

Saturn
Ring shepherds: Prometheus, Pandora
Inner: Janus, Epimetheus
Inuit group: Siarnaq
Gallic group: Albiorix
Norse group: Phoebe
Norse group (Skathi subgroup): Skathi
Norse group (Narvi subgroup): Narvi

Uranus
Ring shepherds: Cordelia, Ophelia, Portia?
Inner: Puck
Outer prograde: Margaret
Retrograde inner: Caliban
Retrograde outer: Sycorax

Neptune
Shepherd moons: Despina, Galatea
Inner: Proteus
Outer large: Nereid
Outer prograde: Sao, Laomedeia
Outer retrograde: Halimede, Neso (there seem to be two sets of outer retrograde moons: the inner Halimede, and Neso and Psamathe on similar orbits)

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 11:59
by ElChristou
ajtribick wrote:Perhaps we should include the largest members of the other satellite groups, to give an idea of the system structure without clogging the display too much...

I quite like the idea; seems reasonable from a display point of view and is quite educative for the default package. The rest could be and official addon downlodable at Celestia's site...

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 15:29
by chris
ElChristou wrote:
ajtribick wrote:Perhaps we should include the largest members of the other satellite groups, to give an idea of the system structure without clogging the display too much...

I quite like the idea; seems reasonable from a display point of view and is quite educative for the default package. The rest could be and official addon downlodable at Celestia's site...

Agreed: this is an excellent idea.

--Chris

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 15:47
by ElChristou
But Chris, are you ready to implement an official download page? Even if it's only for a file, IMHO you should open it, else we will never begin those official packages (textures or data) we have been talking about from time to time...

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 16:00
by cartrite
chris wrote:
ElChristou wrote:
ajtribick wrote:Perhaps we should include the largest members of the other satellite groups, to give an idea of the system structure without clogging the display too much...

I quite like the idea; seems reasonable from a display point of view and is quite educative for the default package. The rest could be and official addon downlodable at Celestia's site...

Agreed: this is an excellent idea.

--Chris
O K, when the appropriate files are changed, I'll include them with the svn executable. Until then I modified the 2 files minormoons.ssc and numberedmoons.ssc to include the class minormoon for all the entries. These are currently available in the zip file. Since Amalthea is in solarsys.ssc, I left it's entry as is. This way users will have something to see that reflects the code change.

I kind of like the way it is now though. A user only need scroll the mouse wheel out or widen the view and type shift m to see system structure.
But.......... :wink:
cartrite

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 16:05
by cartrite
ElChristou wrote:But Chris, are you ready to implement an official download page? Even if it's only for a file, IMHO you should open it, else we will never begin those official packages (textures or data) we have been talking about from time to time...
Shouldn't the executable that Phoenix or myself provide run in the svn celestia folder that wasn't built if it also had the dll's or whatever MAC needs to run? That's an official way to keep the users updated that can't build. Downloading with a SVN client is simple enough.
cartrite

Re: Is Amalthea considered a minor moon?

Posted: 17.04.2008, 16:16
by ElChristou
cartrite wrote:
ElChristou wrote:But Chris, are you ready to implement an official download page? Even if it's only for a file, IMHO you should open it, else we will never begin those official packages (textures or data) we have been talking about from time to time...
Shouldn't the executable that Phoenix or myself provide run in the svn celestia folder that wasn't built if it also had the dll's or whatever MAC needs to run? That's an official way to keep the users updated that can't build. Downloading with a SVN client is simple enough.
cartrite

:oops: I fear you lost me a bit here... I 'm not sure to understand what you mean exactly, but concerning those eventual official addons, the idea was to release Celestia as always and have some officially supported data set or textures. The files could stay in SVN, it's just a question of creating the catalogue page at shatters. In the present case, instead of having ALL minormoons in the default package, you will have only a few ones and up to each users to extend his data base downloading the files and placing them in the extras...