From the darkest part of the object's shadow, you would be able to see a small amount of the light source. There would be a small amount of light that is visible, but it would be faint. On the other hand, from the lightest part of the shadow, you would be able to see much more of the light source. The light source would be far brighter and more visible, and you would be able to identify the source of the light.
Hope this helps! Have a nice day. :)