Create Circle Around Globe

Sorry for probably a basic question, just learning this tool. I have an
image of the world from space where I want to create a circle around,
but having the "back" half of the circle not seen, somewhat like the
rings of Saturn?

I have tried using the circle tool then rubber stamp to "remove" the
circle but the results, well my results are not all that great and I
am thinking there must be a better way.

Thanks!

JimD.

 

Put the circle on a new layer, then mask or delete it. If you put the
circle on its own layer, you will not need to rubber stamp--the globe
will still be beneath the circle.

 

Start with a new layer and create your circle on that.
Go back to the planet layer and use the magic wand to select the black
space.
Back to the circle layer. Layer menu > add layer mask > reveal selection.
Double-click the layer mask and use the eraser tool to erase the half of the
globe that you want the ring to cover.