Which setting is responsible for shadow draw distance?

[Sharpy]

When I installed KSP, I set my graphics parameters pretty high up, as the game was handling that nicely. Got my Munar Landers (rovers) landing, and observing the shadow was very helpful in estimating how far to the ground.

Then I unlocked more parts, began getting my designs more complex and the game began lagging. I cranked graphics way down, and it's better, but now the shadows appear only a meter or two above the surface. I want the rest of gfx parameters down but the shadow to show up way, way early - which parameter changes that?

Edited June 25, 2015 by Sharpy

[Trexation]

When I turned "Shadow Cascades" up to 64 I could see the shadow at around 600m above the surface of the moon. (600m is from kerbal engineer)