paleo Earth orbital configurations

General discussion about Celestia that doesn't fit into other forums.
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kiwi2202
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Joined: 16.11.2007
With us: 17 years

paleo Earth orbital configurations

Post #1by kiwi2202 » 16.11.2007, 23:59

Hi!

I have just started to use Celestia. I would like to create an overview
of the Sun-Earth system for the last glaciations:
from -160 000 years to present day.

I have the orbital parameters values but I don't understand where I can modify it for the earth and where I can specify the epoch of modelling.

Could you help me?

Thank you!

:D

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selden
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Post #2by selden » 17.11.2007, 12:19

My understanding is that the Earth's orbital and orientation parameters have not changed noticeably since the last glaciation. The only difference is in the amount of ice, waterlevels and cloudcover. Those are shown by using a different Texture and a different CloudMap. In other words, you need to use your favorite paint program to create appropriate maps.

They can be shown at the right dates by replicating the current definition of the Earth (which is in solarsys.ssc), changing the Texture name, and adding Beginning and Ending directives to control when the glaciated Textures are shown.

I would use an SSC something like this:

Code: Select all

 Modify "Earth" "Sol" {
    Beginning "-10000 1 1"  # start of current inter-glacial period
}

"Earth-Wurm-Wisconsin" {
   Beginning "-108000 1 1"
   Ending "-10000 1 1"
   Texture "Wurm-Wisconsin-glaciation.*"
# followed by all other Earth parameters except for Texture
}

etc.
Selden

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Chuft-Captain
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Post #3by Chuft-Captain » 17.11.2007, 13:35

There are a couple of addons already showing how this can be done... I think I made a not very serious addon just to demonstrate the principle, but I think the user Maxim made quite a good addon which may be just what you're after. You may find this still on Maxim's website.

I'll try to track down the references for you.
"Is a planetary surface the right place for an expanding technological civilization?"
-- Gerard K. O'Neill (1969)

CATALOG SYNTAX HIGHLIGHTING TOOLS LAGRANGE POINTS

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Chuft-Captain
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Post #4by Chuft-Captain » 18.11.2007, 08:59

A search for keyword="paleo" user="maxim" on the forum yielded the following :
http://celestiaproject.net/forum/viewtopic.php ... ight=paleo
"Is a planetary surface the right place for an expanding technological civilization?"
-- Gerard K. O'Neill (1969)

CATALOG SYNTAX HIGHLIGHTING TOOLS LAGRANGE POINTS

scaddenp
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Location: Dunedin, New Zealand

Post #5by scaddenp » 18.11.2007, 23:09

Well my understanding is that orbitals parameters are constantly changing.
(eg tilt, eccentricity, precession) ie
http://en.wikipedia.org/wiki/Milankovitch_cycles

However, I dont believe Celestia has mechanism for modifying these on a continuous basis.

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selden
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Post #6by selden » 19.11.2007, 01:35

Celestia's builtin planetary ephemeris, VSOP87, is only good for about +/- 3000 years. Beyond that it reverts to standard Keplerian orbits.

However, Celestia v1.5.0 supports ScriptedOrbit and ScriptedRotation functions. You can use them to implement whatever orbital mechanics you want.

For details, see http://en.wikibooks.org/wiki/Celestia/T ... iptedOrbit
and http://en.wikibooks.org/wiki/Celestia/R ... edRotation
Selden


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