In the fight to offer users great and useful programs for free (maybe so as not to lose sight of their rivals at Google), Microsoft have created WorldWide Telescope, which many have now called Google Sky (and itīs also known as Google Herat) from Bill Gates.
In effect, this fantastic program reminds you of Google Sky and its aim is to offer astronomical studies from a web setting, and has been created with the Visual Experience Engine, which converts your PC into a virtual telescope to contemplate the whole world (hence the name).
The quality is such that you can see amazing images of the sky, day and night, letting you apply a wide range of effects like vision x, zoom, crossfade, etc. Imagine an image of a supernova that exploded millions of years ago!
WorldWide Telescope has many educational and astronomical guides from the most famous observatories and planetariums across the USA, letting you view different points of view, with different lighting, etc.