Weird Shadow in VAB

[Rocket Farmer]

So I was just building in the Hab at night when suddenly a large dark circlular shadow passed from one side of the vab to the other on the floor.  It was at least 40% of the size of the VAB and took about 20 seconds to cross the VAB.

 

Anybody any idea?  A transit of the Mun, Minmas or even Eve, Moho etc in front of the planet making it dark even in a lit building?

[Poppa Wheelie]

In Game Time passes while you are in the VAB.  Both Kerbol and Mun (I think - I know it's true for Kerbol) will pass overhead and send light into the building.  Have a look at the ceiling - a large support on rails is moving back and forth across the ceiling.  If extra light is coming in from the top, this moving support will cast its shadow onto the floor.

[Rocket Farmer]

It was the middle of the night and the roof windows were pitch black.  Perhaps the thing on rails you talk about was it if it’s below the lights and really round.

It was just plain strange.