Google Earth is a virtual globe, map, and geographical information program. It lets you fly anywhere on Earth, explore oceans and outer space.
It is free for personal use, and available in Windows, GNU/Linux and Mac OS. It has many great features and tools that can help history and geography come alive:
Google Sky allows users to see galaxies, constellations, celestial bodies, and the movements of planets. It is activated by clicking on the Sky option from the top toolbar.
Street View is a powerful tool that allows users to explore the world through 360-degree street-level imagery. It is not available everywhere. When it is available, an orange figure of a person will show up. You just need to drag and drop the orange person anywhere on the map.
You can also travel back in time through historical imagery by the clock button on the toolbar or from View->Historical Imagery. After you click on it, move the Time Slider onto the date that you want to travel to.
As the old saying goes: “Too much of a good thing is a bad thing”, there is so much information that Google Earth needs to organize it into layers. You can turn different layers on and off by clicking the check boxes. Some examples are: 3D Buildings, Oceans, Weather, Global Awareness, etc.
Besides, Google Earth has a flight simulator. Click on Tools, and select Enter Flight Simulator or press Ctrl, Alt, and the letter ‘A’ simultaneously.
There are many more features: measure distances (Tool, Ruler), take or even create guided tours (Places panel is where you can locate, save, organize and revisit placemarks; You can mark map locations with the Add Placemark button on the toolbar), travel the oceans (Layers, Oceans), etc.