Celestia Forums

Nick Bostrom is actually my boss; we tend to talk great filter over dinner quite often. My take is that any future filter has to be something very hard to predict even knowing it is there, and it has to be large-scale: we could have had space colonies long before big accelerators, so at least some a...

I'm not losing any sleep over RHIC, but the critics have scored a few valid criticisms. Stationary beam targets like the moon produce rapidly moving remnants due to momentum conservation and anthropic selection effects bias our observations, making the cosmic ray argument much more complex than it l...

I have had a little time to test your add-on, Anders, (thanks for that) and although I like the appearance of the cmod travel routes, they do slow my computer down considerably. I would recommend using asterisms for the same purpose- note that they need not be exlusive of each other, and you could ...

There seems to be a lack of deserts. On Earth, there are two broad bands of deserts north and south of the equator because of convection-driven air circulation causing dry air to descend in the subtropics . Also, deserts would tend to form in the rain shadow of mountain ranges. Is it rotating around...

You mean, how do I make the connecting prisms thick prisms? Since I calculate them beforehand, I can use vector algebra: If X1 and X2 are the positions of the two stars, then D=(X2-X1) is the vector that connects them. I chose an arbitrary vector A=<1,0,0> and calculate the cross product with D and ...

Your cmod map looks very nice. It seems worth pursuing even though it takes more work than the asterisms approach. Did precessing the star coordinates to J2000 solve the problem? Thanks! Unfortunately precessing the coordinates did not work. Perhaps I used the wrong formula (anybody have a good poi...

The original (good) papers are: http://pubs.giss.nasa.gov/docs/2007/2007_Kiang_etal_1.pdf http://pubs.giss.nasa.gov/docs/2007/2007_Kiang_etal_2.pdf The first looks at all kinds of photosynthesis on Earth, including purple bacteria and other weird creatures (algae living off near infrared light?!) Lo...

I think tidal forces are the answer. All points on the surface have to be at the same gravitational potential (otherwise they would slide around until they had reached a minimum), but that does not mean the local gravity has to be at the same strength. Tidal forces would make local gravity at the su...

Thanks! I should have guessed this is an old question. Great, now I think I have two options and can go for the simplest/best looking (asterisms are simple, cmod allows me texturing). As soon as I hit the bed after writing my post I immediately realized where the epoch problem was; my cmod object is...

I'm trying to represent the universe of the venerable hard sf rpg 2300AD in Celestia. The game used the Gliese catalogue (2nd ed, 1969) for star positions and a nontrivial "geography" of possible travel routes (due to distance-limited FTL). After a weekend of hacking I have some rather app...