Scale of space in Celestia is not correct?

AlexChan · Post #1by **AlexChan** » 21.06.2006, 23:53

When I saw some picture which were taken by NASA,
the view is different to Celestia,
for example, this one

We can see another moon behind Titan clearly,
but in Celestia, we just can see a dot of light only.
Is there have something wrong in the display rendering of Celetsia?

Malenfant · Post #2by **Malenfant** » 22.06.2006, 00:25

You got a link to that picture on the NASA site? Might help track down what time it was taken so we can see what it looks like in Celestia...

And are you sure that moon is behind Titan? Looks like it's in front of it to me, if it was behind then the dark side of Titan would cover it up (I checked and the smaller moon is definitely in the 'dark side" area)

DonAVP · Post #3by **DonAVP** » 22.06.2006, 01:27

You also need to realize that the focal length of the lens is important when it comes to things like this. If you get the date and time like on the other post you should be able to duplicated the image. You may take some time getting it however. Here is a link showing you what I mean.
cel://Follow/Sol/2004-03-28T07:26:15.21 ... 9&lm=49152
Notice the FOV in the lower right of the screen. What you are looking at is the Earth with the Sun behind it. The POV is out at Jupiter. Now what is the scale :roll:

?

Don

buggs_moran · Post #4by **buggs_moran** » 22.06.2006, 01:44

Definitely get the distance and date from the photo when you see them online. You have to adjust your field of view using < and >. I have recreated many Nasa shots this way.

buggs_moran · Post #5by **buggs_moran** » 22.06.2006, 03:40

Proof of concept...

Cham · Post #6by **Cham** » 22.06.2006, 04:12

According to this web site, the other moon is enceladus :

http://saturn.jpl.nasa.gov/multimedia/i ... ageID=2172

I'm unable to get that view at that date. Maybe my Cassini trajectory isn't up-to-date ?

Malenfant · Post #7by **Malenfant** » 22.06.2006, 05:37

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained on Feb. 5, 2006, using the Cassini spacecraft narrow-angle camera at a distance of 4.1 million kilometers (2.5 million miles) from Enceladus and 5.3 million kilometers (3.3 miles) from Titan. Resolution in the original images was 25 kilometers (16 miles) per pixel on Enceladus and 32 kilometers (20 miles) per pixel on Titan. The view has been magnified by a factor of two.

So I was right, Enceladus IS in front of Titan. Which makes the difference in scale all the more boggling really... Titan is over a million km further from Cassini here and it still looks huge by comparison!

Post #8by **selden** » 22.06.2006, 11:30

Cham,

Many of the orbits used for Saturn's moons are just Keplerian ellipses. As a result, they don't slowly evolve as the orbits of the real moons do.

buggs_moran · Post #9by **buggs_moran** » 22.06.2006, 12:08

You really get a scale idea when you line them all up. (Note: Just in case someone anyone asks, this is forced in the ssc file, it does not happen in reality.)

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Johaen · Post #10by **Johaen** » 22.06.2006, 12:47

buggs_moran wrote:You really get a scale idea when you line them all up...

Oh wow... that is a really cool picture.

I'll have to figure out how to do that on my own...

buggs_moran · Post #11by **buggs_moran** » 22.06.2006, 14:22

It is a good experiment in playing with ssc files, but I can upload it if you like.

buggs_moran · Post #12by **buggs_moran** » 27.06.2006, 16:41

A new rendition with the blue haze associated with UV filters in place. Note, this is not what our eyes would see.

cel://Follow/Sol:Saturn:Titan/2006-02-05T03:17:57.57388?x=ANiXZa2XW3ZkDA&y=CgqTjmTrGqwB&z=VZR+draYx8eO/////////w&ow=0.797619&ox=0.186934&oy=0.570859&oz=-0.054576&select=Sol:Saturn:Titan&fov=0.084645&ts=1.000000&ltd=0&rf=302999&lm=34