Celestia Forums

Hello again...

After some research, it seems that the Great Dark Spot on Neptune is no longer there. After Hubble mapped the planet in 1994, it found that the GDS was gone. Reference http://www.btinternet.com/~patricks.web/astro/nep.htm for more info.

If this is the case then, why are we still showing the Great Dark Spot on Neptune? I thought you people were into realism?

Take care, Bob

I guess I've answered my own question.

We just don't have any better textures, do we? I've seen some rather poor resolution images which were taken by the HST, so the question thus becomes... Do we want to use a newer, poorer texture which shows the actual image of Neptune? Or, do we want to use the old image which is crystal clear?

Even if we use the newer images, there's no guarantee that they show us what Neptune looks like today. Unlike Jupiter, Neptune apparently likes changing its face. Interesting.

Take care, Bob

One reason why the existing texture is being used ... to replay the Voyager encounter ...

http://shatters.net/forum/viewtopic.php?t=1583

-Don G.

This is an obsolete reason; you have forgot we have alternate textures, haven't you ?

This is an obsolete reason; you have forgot we have alternate textures, haven't you ?

That's right!

- - - - - - - -

That's right!

You forgot the alternate textures, but I forgot I haven't to repeat twice

I'm sure a lot of people have already created alternate "current" Neptune textures but for those who haven't and want one, here's one (2K) made with a simple photoshop cloning hack:

http://celestiamotherlode.net/creators/davemc/neptune_current.zip

Don't know how realistic it is since Neptune seems to be a pretty dynamic place but at least the Great Dark Spot is gone. Here's some images to show the difference:

With Dark Spot:


Without Dark Spot:


The install.txt file within the zip archive has all the important stuff.

Dave

Thank you Dave!

Hey, thanks a lot Dave...

You did a very nice job on that texture. I'll see if I can use it
in my next tour. By the way, I really don't think that we're
ever going to get it right though... It seems that Neptune
likes to change its features as it travels around the Sun in
its orbit. I've read where various dark spots (storms?) are
apparent in one viewing, and then completely gone again
the next time anyone takes a close look at the planet. The
planet just doesn't like to stay in one configuration for long.

Take care, Bob

My pleasure guys, it's the least I can do! My thanks to you and everyone on the forum for the help, info, textures, addons, scripts, etc., that make Celestia the great program it is. The collective knowledge and talents, and willinness to share, of people on the forum is incredible!

Dave

By the way, Dave...

I'll be starting the Neptune Tour shortly. Can I have your
permission to use the new texture in this package?

I will be more than happy to give you credit for it (As I always
do) when I use something that isn't mine.

I'm not sure how much of a tour this one will be though. Neptune
doesn't have that much of interest that I have found yet.

Thanks, Bob

Bob Hegwood wrote:I'll be starting the Neptune Tour shortly. Can I have your permission to use the new texture in this package?

Sure Bob, please do. I'll look forward to the new tour!

Dave

Dave,

Okay then, I'll be using it. Thanks *very* much. I have already gotten
started on the tour, but I really don't know what I'm going to do with
this one yet. The planet itself is beautiful and interesting, but most of
its satellites are just dots on the screen.

At any rate, I'll be working on it.

Thanks again and take care, Bob

Me again...

It seems that we also need a new texture for Neptune's Rings too...

Our current textures only list two identifiable rings, when in fact, there
are at least four rings verified as being part of the Neptune system.

If you don't believe me, have a look at the table located at:

http://pds-rings.arc.nasa.gov/neptune/neptune_tables.html

Any comments from the peanut gallery? Or, should I go ahead with
a tour that doesn't depict the planet realistically? The data on this
table is from NASA, and was compiled in 1999.

Thanks, Bob

Bob:
The two rings visible in Celestia are the only two that would be visible to the naked eye if you were close to Neptune (and they're faint enough that I think you wouldn't even see them if your pupils were constricted by Neptune-light) - the other diffuse rings, like Jupiter's ring, stop fewer than one in ten thousand photons, and so would be completely invisible to the naked eye.
It's in the interests of realism that we show Neptune's rings as we do, and don't show Jupiter's ring at all.

Grant

granthutchison wrote:The two rings visible in Celestia are the only two that would be visible to the naked eye if you were close to Neptune

Pardon me if I disagree... As far as I know, the following Voyager picture
relied on no special filters in order to get the view below. It merely used
an occultation device in order to block Neptune's overriding light. Yes?

It's in the interests of realism that we show Neptune's rings as we do, and don't show Jupiter's ring at all.

It's in the interests of realism that my tour scripts *do* show the rings
of Jupiter, and why I intend to have my Neptune Tour show these rings
as they actually exist. Granted, they might be faint and almost invisible,
but if they're really there, then it's just my opinion that they need to be
shown. No?

In the picture above, I can clearly see at least four rings visible.
Also, if you were in space and close to Neptune - as in one of my tour
script locations - wouldn't that also have an effect on whether you could
see the rings or not?

Thanks, Bob

Bob Hegwood wrote:As far as I know, the following Voyager picture
relied on no special filters in order to get the view below. It merely used
an occultation device in order to block Neptune's overriding light. Yes?

Ummm ... no (sorry).
That image is actually assembled from two Voyager 2 photographs, taken from the dark side of the planet, which were carefully targeted to avoid the rather dim crescent of Neptune - the black bit in the middle means "no image", rather than indicating an occlusion device. The fact that the remaining dim edges of the crescent Neptune are still overexposed gives the game away - that's a long exposure image which bears no resemblance to the naked-eye view. (Same old problem as those brightly coloured nebula images that would be just dreary grey if you could see them up close with your bare eyes.)

Bob Hegwood wrote:It's in the interests of realism that my tour scripts *do* show the rings of Jupiter, and why I intend to have my Neptune Tour show these rings as they actually exist. Granted, they might be faint and almost invisible, but if they're really there, then it's just my opinion that they need to be shown. No?

Up to you, of course. Personally, I wouldn't show something that's invisible to the naked eye without mentioning that in the text. (BTW: Did you know that Saturn has a huge invisible ring system that extends well beyond Mimas, and which reflects considerably more light than Jupiter's ring? No-one ever seems to have complained that they can't see it in Celestia.)

Bob Hegwood wrote:Also, if you were in space and close to Neptune - as in one of my tour script locations - wouldn't that also have an effect on whether you could see the rings or not?

For sure. It's on that basis I included the very dim Adams and Le Verrier rings ... because they're about as bright as white paper by moonlight, so they'd show up easily against a black background. But the other rings are much dimmer than black paper by moonlight, which would make them a little tricky to pick out ...

Grant

Hey Bob,

Just a thought...

In the interest of "education of the masses", maybe you could add the "invisible" rings to the existing image by using a dot-dot-dot or dash pattern? Then explaining in the script text that these are invisible to the naked eye, but do exist?

I'll show my lack of astronomical education ... I thought only Saturn had rings, even after running Celestia! Your scripts have shown me otherwise, so don't stop now!

Maybe you could add the same kind of thing to the Saturn tour, since Grant says it has invisible rings too? This stuff simply stupifies me.

granthutchison wrote:That image is actually assembled from two Voyager 2 photographs, taken from the dark side of the planet, which were carefully targeted to avoid the rather dim crescent of Neptune - the black bit in the middle means "no image", rather than indicating an occlusion device.

Okay, I believe you... But now I'm really confused. If that's the case,
then why do the *current* Neptune Ring textures (The ones you approve
of as far as I know) contain the thick layers of dust between the
Le Verrier Ring and the Adams Ring? According to what you're telling me,
this dust should not be seen *anywhere* in the texture. In other words,
why doesn't the current texture show a black space in this area? Using
your methodology to determine what's visible, there should be nothing
there.

Up to you, of course. Personally, I wouldn't show something that's invisible to the naked eye without mentioning that in the text.

Now THAT I don't have any problem with... I just thought that if the
rings *do* exist, then they need to be shown somehow. Does that
make sense?

(BTW: Did you know that Saturn has a huge invisible ring system that extends well beyond Mimas, and which reflects considerably more light than Jupiter's ring? No-one ever seems to have complained that they can't see it in Celestia.)

No, I admit it... I didn't. Of course I've never seen a picture of it either.
But then again, you've confused me some more. If Jupiter's Ring system
is so dim, then how did Celestia get a texture for it? I certainly didn't
create it. If I remember correctly, Praesepe contributed that piece of
the Solar System. How was it contributed if their was no picture of it
to go by?

Sorry, I'm getting a headache.

Thanks for the information. -Bob