Hi Michael,
You can cut/copy and paste nodes into any node. If you don't want to put them inside a node which actually does something itself, such as pasting the nodes relating to a planet inside the planet's node, you can post them into a "neutral" node like a Group, Null or Note. A Note would work quite well because you can then add a description using the node text i.e. "This note has the invisible planet nodes inside it".
To access the internal network of a node context click on it in the network view and choose "Internal network" or use the Action button (gear icon) to the right of the name in parameter views. Choose "Edit internal network" from the menu which pops up. If a node already has an internal network you can also double click on the "+" icon on the right of the node in the network view.
You will probably find you need to recreate some node connections when you paste the nodes, as cutting and pasting will break links to nodes which are not among the nodes being pasted. To put it another way, connections between pasted nodes are maintained but connections to nodes which aren't pasted will be broken.
You can't drag connections from nodes which are outside the node network, but it's still easy to make connections. Simply context click on a node input or output and choose the node you want to connect to from the "Assign shader" submenu. You can also use the Assign shader buttons in parameter views (the green plus icon).
None of this stuff is difficult.
Regards,
Jo
