Amateur stargazers have a new way to explore the heavens - with an update to Google's free global mapping application Google Earth.

This program shows users a globe of the Earth, which they can search for landmarks, high-resolution images and information tagged to the planet by other users. Google says the original application has been downloaded more than 250 million times.

The new feature, called Sky, adds a wealth of astronomical data to Google Earth, including images of more than 100 million individual stars and 200 million galaxies.

At the press of a button, a user sees their perspective shift upwards, revealing the correct constellation of stars for their selected position on Earth. They can then pick out particular stars or planets manually, or using the search field, and zoom upwards to see more detailed images and additional information. Some 20,000 celestial objects can be searched for by name using the Sky feature.

Astronomical imagery and information comes from a number of scientific organisations including the Space Telescope Science Institute, the Sloan Digital Sky Survey, CalTech Palomar Observatory, the United Kingdom Astronomy Technology Centre and the Anglo-Australian Observatory.

Although a number of stargazing programs already exist, such as Starry Night, Redshift and The Sky, Francisco Diego, an astronomer at University College London and president of the UK Association for Astronomy Education says Sky has its advantages. It is simpler than many of these programs, he says, and will appeal to many amateur astronomers because it lets them upload and pin their own images to the sky.

"It could be a kind of astronomical YouTube," says Diego says. "Amateur astronomers will have a fantastic opportunity to display their own work. They discover a lot of supernovae; I think Google are going to be overwhelmed with information."

Jason Chuck, a product marketing manager at Google, hopes the tool could make a useful teaching tool. "Even if you don't know a lot about space, you can zoom out and it can guide you," he says. "If you are teaching stuff in the classroom it can be your guide."