Is there any way to tell when Google Earth updates ?

[billysimas]

I noticed that there are different pictures on Google Earth now than there were a few months ago. I looked at some places where I've lived, and I see a different car in the driveway and one apartment building I lived at was so new that it wasn't even built yet when one Google Earth picture was taken, but I checked it today and it's there now.

When do they update the pictures? Is there any way to tell? Does the software download updates automatically or does it prompt you when it does? Any useful info on Google Earth would be appreciated, I find it so fascinating and could literally spend all day on there.

Adam