Google is celebrating the billionth download of Google Earth, with the popular atlas tool reaching the target in its sixth year of existence.

Google Earth is built on technology developed by Keyhole, which Google bought in 2004, and has proven to be a hugely popular product for the company.

"Today, we've reached our own one billion mark: Google Earth has been downloaded more than one billion times since it was first introducedin 2005," blogged Brian McClendon, VP of Engineering, Google Earth and Maps.

Google earth hits one billion

"That's more than one billion downloads of the Google Earth desktop client, mobile apps and the Google Earth plug-in - all enabling you to explore the world in seconds, from Earth to Mars to the ocean floor."

Google is celebrating with its www.OneWorldManyStories.com site, where it has collected stories from people who have used the tool, including archaeologists, architects and historians.

We're proud of our one billion milestone, but we're even more amazed at the way people have used Google Earth to explore the world," added McClendon.