I like It GooD JoB

Fantastic

nice...

I suggest shading the sphere a little to make it more round, at the moment it looks very flat. Maybe you could also make a selection of the sphere then go to filter-> render -> spherize to give it that extra shape.

The ground doesn't convince me, all the rest seems good.

I agree with Ponti, besides that the overall uni color is kinda boring, the shadow of the tree comes down flat while it should follow the curve of the sphere.

Agrees with Ponti and ROB GL !

First version was better. Now it looks like there's a bite out of the planet.

If you don't know how lights & shades work on a sphere, and you don't have any 3d software to help you ( although you can download google sketch up for free, make a sphere and a tree on top and add light source)
- you can get a small ball of uniform color, a lamp, and cut out from paper the abstract shape of a tree which will be glued on the sphere. Then just adjust the position of the lamp, and take a pic for referece.
If you're not up for all this fun just download Google Sketchup.
About the colors, make something(background) blue/purple to contrast with the brown/yellow.

Very cool idea and nice work author...Love the colors very much...IMHO u should make edges of the tree shadow just a bit softer...best of luck