It's hard to deny how mind-blowing Google Earth can be - I've spent many hours simply flying round the world and getting close up satellite images of random places.

Now Google has launched an add-on to Google Earth that lets you shift your gaze skywards and glide around the millions of stars and galaxies.

As with Google Earth, various layers can be applied to the images. The Backyard Astronomy layer, for example, points out those stars you should be able to see on a clear night - all you have to do is pinpoint your current location using Google Earth first.

Combined with services such as Heavens Above - a site where you input your location and it will provide you with details of visible passing satellites and the like - home astronomy has never been more accessible.

You can't zoom into planets, such as Mars and Venus, and scour their surfaces in the same way as Google Earth, but it's still a fascinating service.