Error in solarsys.ssc Mercury definition

Report bugs, bug fixes and workarounds here.
Topic author
granthutchison
Developer
Posts: 1863
Joined: 21.11.2002
With us: 22 years

Error in solarsys.ssc Mercury definition

Post #1by granthutchison » 03.12.2002, 00:55

There's a typo in the solarsys.ssc definition of Mercury. It should read

Code: Select all

RotationPeriod 1407.509

not 1047.509. The correct setting maintains the 2/3 spin/orbit resonance, and allows you to watch the Sun moving backwards at noon when Mercury is at perihelion.

Grant

Calculus
Posts: 216
Joined: 19.10.2002
With us: 22 years 1 month
Location: NY

Post #2by Calculus » 03.12.2002, 01:09

I actually tried to watch the sun moving backwards but it didn't work.
Now I know why
Thanks again Grant
---Paul
My Gallery of Celestial Phenomena:
http://www.celestiaproject.net/gallery/view_al ... e=Calculus

Topic author
granthutchison
Developer
Posts: 1863
Joined: 21.11.2002
With us: 22 years

Correct Mercury orientation

Post #3by granthutchison » 03.12.2002, 01:20

If you would like to get Mercury correctly orientated, too, use the following

Code: Select all

   RotationPeriod 1407.509405
   Obliquity   7.01
   EquatorAscendingNode 48.42
   
   RotationOffset   291.20

(There's a 180-degree error in the EquatorAscendingNode in the original.)
The RotationOffset is correct for a texture map with a central meridian of zero degrees. It brings the zero and 180 degree meridians to their correct positions at the "hot poles" - the two areas that get local noon at perihelion.

Grant

chris
Site Admin
Posts: 4211
Joined: 28.01.2002
With us: 22 years 9 months
Location: Seattle, Washington, USA

Post #4by chris » 03.12.2002, 03:44

Calculus wrote:I actually tried to watch the sun moving backwards but it didn't work.
Now I know why
Thanks again Grant

Aha! I'd been wondering about this too . . . Now I'm finally able to see the double sunrise!

--Chris

billybob884
Posts: 986
Joined: 16.08.2002
With us: 22 years 3 months
Location: USA, East Coast

Post #5by billybob884 » 03.12.2002, 04:12

so how do you view this "double sunrise"?
Mike M.

TacoTopia!

Topic author
granthutchison
Developer
Posts: 1863
Joined: 21.11.2002
With us: 22 years

Post #6by granthutchison » 03.12.2002, 13:56

billybob884 wrote:so how do you view this "double sunrise"?

Having pasted in the new definition for Mercury that I posted, go to latitude 0, longitude 90 on Mercury, 0.002km above the surface. Track Sol, and speed things up a bit. You should see the Sun getting gradually bigger as it drops towards the horizon, setting by a tad more than half its width and then popping back up again. Repeat performance at sunrise - up, down, up.
Nice test that I've got all the numbers right, since that effect should only be visible on the horizon at 90 degrees and 270 degrees longitude.

Grant

Calculus
Posts: 216
Joined: 19.10.2002
With us: 22 years 1 month
Location: NY

Post #7by Calculus » 03.12.2002, 18:54

I made screenshots of a sunset on mercury.
Have a look at my gallery.
---Paul

My Gallery of Celestial Phenomena:

http://www.celestiaproject.net/gallery/view_al ... e=Calculus

chris
Site Admin
Posts: 4211
Joined: 28.01.2002
With us: 22 years 9 months
Location: Seattle, Washington, USA

Post #8by chris » 03.12.2002, 19:36

Calculus wrote:I made screenshots of a sunset on mercury.
Have a look at my gallery.

That's a great image! I've never the Sun's path through the sky illustrated so well. So how do you create your 'strobe' images?

--Chris

Calculus
Posts: 216
Joined: 19.10.2002
With us: 22 years 1 month
Location: NY

Post #9by Calculus » 05.12.2002, 01:23


That's a great image! I've never the Sun's path through the sky illustrated so well. So how do you create your 'strobe' images?

--Chris

Thanks Chris
I actually make several captures and assemble them. In this particular example, I also removed the sun flare to get a clear effect.
---Paul

My Gallery of Celestial Phenomena:

http://www.celestiaproject.net/gallery/view_al ... e=Calculus


Return to “Bugs”