As your friendly tips guru, I try to keep pretty well-acquainted with all things Earth. But I recently found myself thrown for a loop when the lights got turned off on my virtual world. Google Earth seemed to be in a permanent state of nighttime -- and while I didn't mind flying by night for a while, I was stumped as to how to get things back to normal.

Combing the Google Earth Help Forum, I found I wasn't the only one perplexed. The cause, as it turns out, is the NASA Earth City Lights layer, that darkens the planet so you can see light emissions from urban areas. It was switched on, and I didn't know it. You can find it in the Layers panel by clicking Gallery > NASA > Earth City Lights. If you turn off the layer, you'll find it sheds some light on things (literally!).

Layers hold the key to most of the content available in Google Earth and, since there are so many, it's not always easy to remember which layers to toggle on or off to get the content you want. Looking for the name of a street? Make sure you've turned on the Roads layer. Can't dive under the ocean? Chances are, it's because your Terrain layer is turned off.

Sometimes the layer you need isn't quite intuitive: If you're having trouble viewing the shipwreck of the Titanic, it's probably because you need to turn on your 3D Buildings layer (and you'll be able to check out plenty of other underwater 3D models, too).

So, when it seems like there's something missing (or, when it's too dark to tell), the Layers panel can be your golden ticket. And don't be too quick to flip the switch back to daytime on the City Lights layer -- there's plenty to see under cover of darkness, too.