500
Draw a circle, in the top right corner draw the sun.
Now shade the circle to create a sphere or ball. Shade for where the cast shadow would fall on the ground, and how the ball is shaded.
Remember where the sun is gets the most light and will be the brightest. Where the sun is far away from will be the darkest.
Shadows are stuck to our feet, we aren't Peter Pan, and make the same shape as the object casting it. Just like your shadow in the sun looks like a person.