Tribes 1 Legendz

So, I finally downloaded Tribes 1.40 and started making changes. I converted the tga image of this planet (from Hudbot) to png and it appears messed up like this. The image had transparent background, which apparently the game doesn't recognise or something. The only way to hide it was painting the background with the colors of the upper pixels of the sky images. Is there a better way to fix this and allow transparent background in 1.40?

Open another planet image and check the color value in the corners. I suspect black gets covered to transparent by tribes, and what appears black in tribes is actually slightly off black, like a really dark gray or brown.

Doesn't work

Just make the planet square. Texture it after the Allspark from Transformers.

I prefer them like those in our solar system