Re: [SPACE] System Design help? (star systems that is...)
 

No problem. It was kinda fun to fiddle with the design constraints to make a specific system. Usually I just go by the dice rolls and work from the "dirt up" rather than from the "story down".

The three planets will all be fairly different, and I think you should be able to easily fudge the outermost one into an Earthlike world that's perpetually glaciated, but has enough photosynthetic life to create a marginal, but breathable atmosphere (a thick atmosphere will help warm it, too.)

Personally, I want to see how the system turns out once you get it the way you like it.

Re: [SPACE] System Design help? (star systems that is...)
 

that Inner planet, 'Hot in the summer.' Easy solution, give it an almost spherical orbit, same temperature all year round, probably like a semi-tropical rainforest or something like that. outer planet, thick atmosphere. Done and done.

I'm not much of a number cruncher, don't have the books, and definitly don't know my astronomy so scuse any blatant stupidity.

Re: [SPACE] System Design help? (star systems that is...)
 

Unfortunately, that's not what causes summers to be warmer than winters. Witness the fact that our world has summers at opposite times of the year depending on whether you are in the northern or southern hemisphere. This would be impossible if it was caused by proximity to the sun, because you can be closest to the sun at two times during the year no matter what your orbit looks like.

However... he's got the right concept. Give your innermost planet an axial tilt of 0. Then you won't have any seasonal effects. Technically this only shifts the problem from a seasonal one to a latitude one. The equator would be too hot. But, the temperate and polar zones might just be ok.

Re: [SPACE] System Design help? (star systems that is...)
 

Well, usually eccentricity doesn't cause the seasonal changes. However, if a planet had an extremely eccentric orbit it could cause climatic changes similar to those caused by axial tilt (though the whole planet would have summer and winter at the same time, rather than opposite in the two hemispheres). Combined with an axial tilt this could cause some extremely different climate conditions between the Northern and Southern hemispheres.

If the eccentricity works to enhance the seasonal variations (perigee and apogee lining up with axial tilt) you might wind up with a Northern climate which has a warm summer but bitter cold winter while the Southern hemisphere would have blistering hot summers but mild winters. Or, if the eccentricity works to mitigate the seasonal variations (perigee and apogee being at right angles to axial tilt) you'de have mild summers and winters in farther reaches of the the Northern and Southern hemispheres, but the equatorial region would swing between very hot and very cool spring and fall seasons. Further, axial tilt tends to wobble over thousands of years, meaning you'de have long climate cycles where eccentricity enhances seasonal variances, followed by periods where it mitigates seasonal variances.

Re: [SPACE] System Design help? (star systems that is...)
 

Doing some quick checking for Space 3e, the only stars that appear to be able to have two worlds in the habitable zone are G-V and G-VI, and that puts one planet on each edge of the habitable zone.

Re: [SPACE] System Design help? (star systems that is...)
 

That may be...but I need UP-To -DATE 4th edition references. That is what I and the rest of us are using.

Thanks for checking tho...

- E.W. Charlton
(4th edition books are really good...)

Re: [SPACE] System Design help? (star systems that is...)
 

Brandon, I realize (and fully respect) that you feel 3e is superior to 4e, but that doesn't make the 10 year old science in 3e superior to the current astrophysical models.

Re: [SPACE] System Design help? (star systems that is...)
 

My post had nothing to do with what I thought was superior. It was about using the most recent RPG astrophysical model I have to help the OP.

And, that being the case, I should have used the data from GURPS Traveller: First In, instead; while it came out the same year as Space 3e, it uses more recent science. It looks like it probably isn't possible to have two planets in different orbits both fall in the life zone.

Re: [SPACE] System Design help? (star systems that is...)
 

Brandon,
The Astrophysics and science in SPACE 4/e - is based on what was in FIRST IN. BUT it is even more "up-to-Date". Thats a big chunk of the reason that I bought it. This is one case where the more RECENT the edition and book is the better .

Thanks for trying to be helpful tho.

- E.W. Charlton

Re: [SPACE] System Design help? (star systems that is...)
 

I really don't use the system generation rules from First In (which is why I didn't think of it initially). They may be more realistic than Space 3e, but I don't think all the added complexity is worth it.Then again, I was pretty satisfied with the pre-Book 6 CT way of rolling up worlds and systems.