Celestia Forums

Hi there!

I run the Extrasolar Visions site which I have been gradually updating to reflect more recent research and discoveries. About six months ago I started using Celestia as my primary rendering tool as it takes care of most of the calculations and is specifically designed for rendering planets.

Anyway, I've been toying with rendering the asteroid belt of HD 69830 and have come up with this prototype...




Is this convincing? I'm attempting something along the lines of the image that was put together by NASA... http://www.spitzer.caltech.edu/Media/re ... -10c.shtml

-John

Hello,

I don't know for the scientific accurancy, BUT I love the picture... Is this available?

It's not available yet. Just a test. Though, I'm strongly considering releasing an extrasolar add on that would include this and a lot of other stuff I've been working on for my site.

-John

It looks great!

You might be able to simulate the additional haze around the star that's shown in the NASA picture by modifying flare.jpg. It's in the root textures directory.

Hadn't thought of that, but wouldn't modifying flare.jpg affect all stars? Is there a way to set a flare style for a specific star?

Also, I neglected to mention the technique I used to get this effect...

Basically, the belt is a combination of three "planets", each with a zero orbit that puts them inside the star. The first has a giant ring that extends 100,000,000 km. The second is highly oblate and has a atmosphere height the same value as the ring width. The third is the same as the second, only less oblate and smaller. The actual radius of each "planet" is ~600000 km, so the "planets" themselves are hidden inside the star. And, of course, the radius of each is slightly different than the others to prevent them from "blinking".

Only flaw so far is that you have to turn off ring shadows. Otherwise the "planets" cast a long thin shadow on the ring. You can make the ring emissive, but then you get an odd brightness gradient across the ring. I've toyed with using a null mesh to remove the planet shadow, but this tends to crash the program.

Also, zooming in on the star penetrates the atmospheres, so you'll get the same kind of blinking and odd effects as when you get too close to a planet with an atmosphere, only more so because there are two atmospheres overlapping.

-John

Yes, modifying flare.jpg would modify the appearance of all stars. My suggestion was more for generating specific artwork.

A more general possibility might be to create a 3D model of the right shape and transparency and define it as a planet with an SMA of 0 and Period of 1e32 so that it extends around the star.

Another would be to define an appropriate cloud texture around that fake planet.

If you use Celestia v1.4.0pre6, you can use a 3D model as a Mesh for the star itself. Unfortunately, Celestia seems always to draw stars as an opaque light source; maybe a future version of Celestia will be able to show translucent coronal effects and haze like this.

Very very interesting ...but I would turn off galaxy rendering.
I would also be quite curious about what graphic card do you use.

In the Physics & Astronomy Section I wrote:Posted: Thu Apr 21, 2005 5:17 pm
Post subject: Spitzer Detects a Possible Alien Asteroid Belt.

I received an interesting e-mail from NASA news yesterday. Here's a link to the story on the main Spitzer website;

http://www.spitzer.caltech.edu/Media/re ... ease.shtml

Maybe there is some potential here for a future Celestia add-on ?

John,
Thank you for trying to add this interesting recent discovery to Celestia.

John Whatmough wrote:...The first has a giant ring that extends 100,000,000 km. The second is highly oblate and has a atmosphere height the same value as the ring width. The third is the same as the second, only less oblate and smaller....

As Selden, I think a 3D model of disk can solve the problem of ring shadows...

John:

The effect is spectacular. I am anxiously awaiting the add-on. I would like to use it in Celestia's educational activities, which I write and maintain for use by teachers around the world.

In particular, will the disk haze have some sense of debris in it (simulating nebula rubble coming together to form asteroids and accretions?) In other words, as an asteroid belt, it would be great to also see some asteroids inbedded in the disk/haze layers. Is that possible?

Anyway, looking forward expectantly to the add-on.



Frank G

Damn. That is a ridiculously cunning way to get the hazy disk effect there. Great stuff!!

any advancement on this add-on yet, I have been keeping my eye on this for a while now

looks fantastic

Cripes...where you been!?

regards...bh.

John,
Big fan of your website! Love your ARTWORK! I often reference your site to get ideas of how Planets and Stars might look up-close and personal. I understand your artwork is consistant with astronomical standards. Wow, the thought of the possibility that you (A noted artist) might make textures for Celestia is exhilarating. I especially enjoy your Brown Dwarf concepts!
Post Script: Amazing effect with that ateroid belt!
I stand in the shadow of GREATNESS!

About the Artist

Google Images

EXTRASOLAR VISIONS

THE ACCOUNTS OF THYRENACIA

The Union Leader and New Hampshire Sunday News

Posted: Thu Sep 15, 2005 2:21 am Post subject: A Terribly Sad Announcement

Posted: Fri Sep 16, 2005 12:57 pm Post subject: John Whatmough

If anyone has possibility of contact with the family, I think I can speak for the whole Celestia community in this case when I say it is a tragic loss and we send our condolences.

I sent an email to a close friend of his who made the official announcement in the extrasolar visions forum. Along with a few others who did likewise, I think we've conveyed just how much of an impact both his life and his passing has made on the 'Net and, I daresay, off of it as well.

...John...

What a tremendous loss to the Astronomical community! An irreplaceable asset! He's a hero who was trying to save his own son! "No greater love hath any man than, to lay down his life for his friends." He will be sadly missed by us all. My sincerest condolences to his family! I really don't know what to say, I'm shocked and deeply saddened.