Make a new image - 150 x 150 pixels - transparent
background.
Create a new layer. Have white as your foreground- and
black as your background color. Create a circle with the
Elliptical Marquee Tool. Now select the Radial Gradient Tool,
and fill the selection like in Ex. 1.
Ex.1
TIP:
Hold the shift key down to make a perfect circle.
Your image should now look like Ex. 2.
Ex. 2
Now it is time to chrome
your sphere. To get the effect just go to
Image-Adjust-Curves, and use the following or create
your own combinations.