Draw a circle using ellipse tool :-
Apply gradient overlay as shown :-
Colors used :- #FFFFFF (white), #1A8DB9 and #B2D6E6 .
Add #384E77 color outside stroke in it :-
Now, draw a black color circle as shown :-
Add radial gradient overlay as shown :-
Color used :- #FFFFFF #4FC2E1 #374D75
Here what you get after adding gradient overlay :-
Now, reduce its opacity to 60%. Copy (press alt and drag the layer) and place the layer as shown :-
Now, draw this shape with ellipse tool :-
Reduce the fill to 40%
Duplicate, increase its size and place two more layers of it as shown :-
Finally, if you like you can add shadow as shown :-
Feel free to post your experience/comments/suggestions.