Eclipse

Eclipses are possible in KSP, as the Mun isn't in a offset orbit, like the Moon in real life. Because of how the game is made, it does not get dark; however, solar panels will say that they are blocked by the planet in the way and not work. Below are some pictures of a Kerbolar eclipse, as viewed from Kerbin and LKO (Low Kerbin Orbit).

A full Kerbolar eclipse can be observed while landed at KSC starting after game time Year 1, Day 351 - 5h, 40m, and ending (being partial again) somewhere around Year 1, Day 352 - 0h, 22m. Not sure of other occurences or locations, but this one at KSC is confirmed (unless game times and positions of bodies varies between players). Apparently a Kerbolar eclipse happens every 6 days, according to a random online source (too lazy to do math or test).

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  An early stage of an eclipse where the Mun blocks Kerbol

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  Another early stage of a Kerbolar Eclipse

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  An eclipse at the fullest stage.

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  A screenshot showing that solar panels are blocked during an eclipse

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  Proof that eclipses don't dim the lighting.