Why don't you precomp all the planet layers into one comp,
one layer and then animate the rotation of that layer. Duplicate
the Head layer and put it on top of the Planets layer and the
planets in the back will look like they are going behind the head.
Looks like the Planets in the front are far enough from the head
that they won't get covered by it.
Johny5's suggestion is going to be more trouble than it's probably worth and would involve some complex expressions to keep the planets oriented towards the camera.
The easiest way to do this is to use 3D layers and nulls. If you want all of the layers to rotate at the same speed then you only need one null.
- Start by importing all of your layers and leave them at the center of the comp
- Add as many nulls as you need for the different speeds
- Make all layers 3D
- Add a camera to the scene with a standard lens (about 50mm)
- Select all of the layers that are going to be planets and the Head (center) layer
- Press Alt/Option + Ctrl/Cmnd + o to bring up the Auto Orient panel and set all planet layers and the head (center or sun) to Orient Towards Camera
- Select the planet layer you want to be closest to the head (sun) and make it the child of the 3D null at the center of the comp
- Select 2 Views from the Comp Panel options - set the second view to top (default)
- With the layer still selected press p to reveal the position property and adjust the Z value to move the first planet away from the camera
- If all of the planets are going to move at the same speed rotate the null 36º (you have 10 planets in your example)
- Repeat the parenting, the move in Z and the rotation for each planet
- After all the planets are distributed in 3D space animate the rotation of the null
- If you want the planets to move at different speed attach each planet to it's own null and then animate each null
- Fine tune the camera position to get the angle and perspective you want
If you have problems with planets lining staying square to the camera then you have to open up their rotation properties and make sure that all rotation and orientation values are set to 0º so Orient towards camera will work.
It is easiest to set this kind of a project up if you have the view options for the comp panel set to show the camera always so you can see where the edges of the frame are in the top view. Let me know if you have any problems. This is really basic 3D animation and you should get comfortable using multiple views and arranging layers in 3D space.
I would try to:
Center the anchor points of each layer to the planet center.
Create a path that would be around the head if it were 3d
Copy the path data to the position property of each planet layer
Offset the position keyframes of each planet layer so the planets are whatever distance away from each other you want them to be
Now they should all be moving around at the same speed. All you need to do is make it appear they're passing behind the head.
Precompose all the planets and use a track matte to make it look like they're disappearing behind the head.
I suppose it depends on the specifics requirements of your shot