Celestia Forums

I have been working on this for a while now, but I wanted to bring it up into the public to see how you think they are. The current textures for extrasolar planets are really good for a start, but do have limitations. For instance, they are so small that they give very little to the imagination, and are not too planet-like (meaning they look like a giant paintball). Don't get me wrong, I am talking about the actual size of the images. They are too small to really make out anything.



Here is my work in progress textures for Extrasolar planets (in order, types I, II, III, IV, and V). I plan on working on them before I make them downloadable for the public. I just wanted to find out if I am on the right track. They are still a work in progress, so don't be mean

The rationale behind why I made the textures the way I did was because they are intended to be generic - the planets themselves will likely have a wide range of different appearances thanks to varying rotation rates, orbital eccentricities, and compositional differences.

As for your textures, I am somewhat curious as to why you have depicted the class III planet with cloud patterns, when the class III planets are cloudless. Your classes IV and V appear to bear no relation to any of the hot Jupiter atmospheric circulation models which have been published (the slow rotation rates thanks to tidal synchronisation are predicted to yield circulation patterns very different from rapidly rotating planets like Jupiter), nor do they appear to have any relation to the colours predicted from the Sudarsky spectra (the current textures are based on Grant Hutchison's integrations of the Sudarsky et al. spectra to get the overall colours)

A deficiency in both the Celestia default textures and your ones is that observational evidence indicates that hot Jupiters are actually extremely dark, reflecting almost no light. Instead the planets would glow from thermal emission - pL planets transport heat to the darkside as well, whereas the hotter pM class planets do not. As far as I am aware, there is no observational evidence for the increase in albedo in class V planets caused by silicate clouds.

ajtribick wrote:The rationale behind why I made the textures the way I did was because they are intended to be generic - the planets themselves will likely have a wide range of different appearances thanks to varying rotation rates, orbital eccentricities, and compositional differences.

You made them?? I wouldn't have guessed.

ajtribick wrote:As for your textures, I am somewhat curious as to why you have depicted the class III planet with cloud patterns, when the class III planets are cloudless. Your classes IV and V appear to bear no relation to any of the hot Jupiter atmospheric circulation models which have been published (the slow rotation rates thanks to tidal synchronisation are predicted to yield circulation patterns very different from rapidly rotating planets like Jupiter), nor do they appear to have any relation to the colours predicted from the Sudarsky spectra (the current textures are based on Grant Hutchison's integrations of the Sudarsky et al. spectra to get the overall colours).

The reason for the class III clouds was for texture. Yes I added a cloud texture, but it is very light to invisible. Just looking at a blue dot looked a bit bland, so this was for aesthetic purposes.

As for the classes IV and V, I am aware that I didn't have the right cloud structure. I currently had to work with what I had until I could find (or make) the proper could layer.

ajtribick wrote:A deficiency in both the Celestia default textures and your ones is that observational evidence indicates that hot Jupiters are actually extremely dark, reflecting almost no light. Instead the planets would glow from thermal emission - pL planets transport heat to the darkside as well, whereas the hotter pM class planets do not. As far as I am aware, there is no observational evidence for the increase in albedo in class V planets caused by silicate clouds.

Thank your for your advice. Like I mentioned before, this is a work in progress project of mine. So I have plenty of time to fix my mistakes.

Yes well it's quite tricky to figure out what to do for the exoplanets: the problem is the Sudarsky model doesn't seem to very well describe the behaviour of hot Jupiters - reality seems to make them all sort-of class IV (but even less reflective than predicted), and we haven't got the necessary observations of intermediate temperature exoplanets yet, so coming up with a consistent model for the various Jupiter-type planets is difficult. One of the things that I think is important to know before committing anything to the Celestia distribution itself is the location of the T/Y transition: as far as I am aware, brown dwarfs have been found with temperatures below the predicted transition between Sudarsky classes IV and III (~800 K), but are still classified in spectral type T.

Here is version 2 of my textures. I have tweaked some of the issues that were brought up by ajtribick. I believe classes I and II are okay enough. I have made the lines of class III nearly gone. Please do not mistake them for clouds, the line differences are there to give the planet jovian characteristics.

As for classes IV and V, I think I'm on the right track. I might need to work on them a bit more, but here is a work in progress. I have found a way to make them look reflective around the equator region. Class IV is less reflective than a class V.