OT: Cassini takes first picture of Saturn

[Raul.]

The probe is still 20 months away from its target but a few days ago took this picture of Saturn and Titan:






More details here: http://www.jpl.nasa.gov/releases/2002/r ... 02_202.cfm

Can't wait for July 2004. Well, to be honest what i'm really looking forward is Huygens landing (or whatever it turns out) on Titan (Jan 2005).

[aaronsb]

Here's the same image taken from celestia, with about the same distance and date that the real image was taken.

[Raul.]

Wow, nice picture aaron. Besides slightly different colors on Saturn clouds and the brighter moons they look almost identical.

[selden]

Raul,

I hope you realize that you, too, can take thtat picture using Celestia:

Download the Cassini xyz file, GoTo Cassini, Select Saturn, Center, and increase the telescopiic magnification until the field of view is down to about 15 arc minutes.

Aaron,

Thanks for reminding us why Celestia is such a great utility!

[Rassilon]

Can't wait for July 2004. Well, to be honest what i'm really looking forward is Huygens landing (or whatever it turns out) on Titan (Jan 2005).

I cant either...Titan is by far me favorite moon in the solar system...

[HankR]

Although I'll admit it's hard, I'm trying not to get too excited in advance about Cassini/Huygens, in view of the dismal track record of recent solar system exploration missions...

- Hank

[billybob884]

thats an amaizingly scary likeness. almost too alike...

[selden]

Off topic response:

Mike, if that's scary to you, you should avoid seeing the movies "The 13th Floor", "The Matrix" and "Existens". They all postulate that we are living in a simulation and don't know it.

[aaronsb]

One thing I noticed is that there is no shadow of the ring on the foward side of the planet, only the backside. I wonder when that will get fixed?

[selden]

Aaron,

I dunno if you're commenting on the Cassini picture or the Celestia picture, but in both cases I think the shadow is being obscured by the rings themselves.

Added later:
More seriously, if you're seeing the shadows on the backside of the planet in Celestia, it means that you've got the unrealistic "ambient light" turned on, although I agree it'd be nice of the far-side shadows could be eliminated. The front-side shadows look fine on my system. (GF4 Ti4200) Could you be confusing them for the coud patterns? Remember that Saturn is tipped way over, so that the rings are at about a 45 degree angle with their shadows only across the "top" of the planet.

[aaronsb]

If you look at the cassini picture, there is a small sliver of shadow from the ring on the sunside of the planet. That small sliver is missing from the celestia version.

Planetary rings cast shadows on the sunside as well. There aren't any in celestia 1.2.5pre6 at least. :?

[selden]

Aaron,

Strange. The ring shadows look fine on my system running 1.2.5pre6. Here's an example:

The full sized snapshot is at http://www.lns.cornell.edu/~seb/celestia/saturn-ringshadows.jpg

Note that the grey stripes at the top (the shadows) are not quite parallel to the rings or to the cloud pattern borders that can be seen below the rings. If your system isn't rendering them, it may be due to a ddiference in graphics hardware and Chris needs to know about it. I'm using a GF4 Ti4200 with Detonator 40.72 drivers.

p.s. In order for your system to be able to render the shadows on the planet, it needs to support "vertex shaders". Try typing a Control-V to enable them. Sometimes they can be turned on that way even if the option is greyed out in the Render menu. Shadows cast by the planet onto the rings are done differently and don't need either pixel or vertex shaders.

[chris]

The shadow cast by rings onto the surface of a planet is only visible if you have a GeForce3 or GeForce4 Ti right now (though I will fix this . . .)

The interesting thing about the Cassini picture is that the ring shadow is completely black. I deliberately toned down the darkness of the ring shadows in Celestia because the black shadow looked strange to me. Guess I was wrong . . . In the images of Saturn taken from Earth, the rings always nearly completely obscure the ring shadow. The Voyager images arrived at Saturn at a time when the rings where nearly edge-on to an Earth-based observer, so the ring shadow was just a thin, dark line at the equator. With Cassini, we have our first look at broad ring shadows on Saturn.

--Chris

[chris]

So I did a quick experiment and turned on black ring shadows. Here's an image from Cassini's location on Nov. 1 (I'm using the .xyz trajectory):



(ignore the incorrect moon positions--I'm doing some orbit work at the moment)

It's apparent in the image from Celestia, that the illuminated sliver in the otherwise shadowed top right portion of Saturn is a result of light shining through the Cassini Division. Cool!

--Chris

[billybob884]

Off topic response:

Mike, if that's scary to you, you should avoid seeing the movies "The 13th Floor", "The Matrix" and "Existens". They all postulate that we are living in a simulation and don't know it.

First of all, i've seen the 6th day, which doesn't sound to different. Second, i was KIDDING!
why does everyone take me so seriously on this forum?

[Anonymouse]

Say... do you suppose it's possible that the Cassini spacecraft has actually failed and that NASA is engaged in a huge cover-up and is using Celestia to generate these images of Saturn?

[selden]

Mike,

Letters on the screen can't grin at us the way you probably felt.
That's why emoticons (smileys) can be important.

"Dark City" is another similar movie.

[selden]

Anonymouse,

Naah. Their pictures aren't as good as Celestia's!

[Stargazer_2098]

Finally a mission that havn't gone awry!
Cassini is on its right course, at the right speed, at the right angle. Everything is going by the book.

Cant wait to see more close-up picutres of Saturn taken by the Cassini, but what I'm really looking foreward to is the probe landing on Titan.

It is possible that Titan has life; tough this would be very very very different from Earth-life.

One thing is for sure: I cant wait till 2004.


Stargazer.