Although it is a common misconception that Google Earth images are real-time, they are not. There are, however, two ways to view nearly real-time satellite images on Google Earth. For three-hour old weather images, look for the Clouds layer, found under the new Weather layer folder. NASA also has a layer called DailyPlanet which shows the entire Earth, continuously updated in real-time at a medium resolution. For more Google Earth tips, read the Google Earth Blog.