[bill875] “How do I get just the selection (the earth) into the after effects comp without the white border?”
Are you saying that the mask on your Photoshop layer isn’t exact? Or are you saying that the white ‘background’ layer in Photoshop is showing? If the latter: when you import your footage into After Effects make sure you don’t import the Photoshop file as “Merged Layers,” this will effectively flatten your file’s layers into one. Instead you want to choose a layer in the Photoshop file to import. Alternatively you could just delete the white ‘Background’ layer in Photoshop so that you can see the checkered pattern (meaning those pixels are transparent) behind the earth image.
If you are trying to remove the earth from a layer with a white fill then you’ll just need to make sure your selection doesn’t include any of the white on that layer when you use Layer > Layer Mask > Reveal Selection.
It’s hard to know exactly what the problem is without more information about the Photoshop file(s). I don’t know how many layers are in the file, if there’s an alpha channel, etc.