Have you ever wondered how it feels to explore space without any limitations or fears? How it feels to be in search of a star or a planet, even without to be an astronomer? Well, from today on, you may just get a hint about those kind of feelings thanks to the new add-on introduced by Google in its Google Earth program: Sky.

With this new feature, you may float through the sky as seen from our planet and, according to Google, you have no less than 100 million individual stars and 200 million galaxies to view and explore.

"We’re excited to provide users with rich astronomical imagery and enhanced content that enables them to both learn about what they’re seeing above and tell their own stories," said Lior Ron, Google Product Manager. "By working with some of the industry’s leading experts, we’ve been able to transform Google Earth into a virtual telescope."

Sky combines high resolution imagery and informative overlays in order to create a unique playground for visualizing and learning about space. The images used to recreate the sky are offered the Space Telescope Science Institute (STScI), the Sloan Digital Sky Survey (SDSS), the Digital Sky Survey Consortium (DSSC), CalTech’s Palomar Observatory, the United Kingdom Astronomy Technology Centre (UK ATC), and the Anglo-Australian Observatory (AAO).

The Digitized Sky Survey comprises photographic surveys of nearly the entire sky and contains about a million objects. The Sloan survey comprises images of hundreds of millions of much fainter objects and covers more than a quarter of the sky.

"Sky is a very cool new feature for anyone who has ever looked up at the sky and wanted to know more," said Sally Ride, former astronaut and CEO of Sally Ride Science. "I think this is a great tool for satisfying that curiosity."

And you will never get bored as Google has introduced seven amazing layers to illustrate celestial events. For example, thanks to Constellations, you may learn about the stars that make up a specific constellation from Cassiopeia to Andromeda. All you need to do is just to click the desired name and the layer will connect the points of constellations through space.

If you want to learn about the Planets or the Moon, Sky offers two layers which display animations of two months of both lunar positions and moon phases and the position of the planets in the sky two months into the future.

For those of you who want to became an astronomer, Sky may be a perfect start as the Google’s add-on introduces a layer called the Backyard Astronomy which is intended to let users click through a variety of placemarks and information on stars, galaxies, and nebulae visible to the eye, binoculars and small telescopes.

And you will feel encouraged to explore the sky thanks to the Users Guide to Galaxies layer, which enables users to go on virtual tours through different types of galaxies, from Ursa Minor Dwarf to the Milky Way.

The Life of a Star layer takes the user on a tour through the different stages of a star’s life cycle.

Also, the Hubble Space Telescope Imagery layer provides users with over 120 high-resolution images provided by the Hubble Space Telescope, NASA/ESA’s renowned orbiting telescope.

"You have seen the Hubble images of objects such as the Eagle Nebula, the so-called pillars of creation," said Carol Christian, an astronomer at the Space Telescope Science Institute and one of the developers of the Sky in Google Earth project. "With Sky in Google Earth you can see where the objects are located in space, including the constellations in which they reside. Then you can discover other cool objects in nearby regions of the sky. And you don't have to know anything about astronomy to use the program."

"This is a fun program for amateur astronomers, scientists, educators, and the public to explore space," Christian adedd. "It is like having the heavens at your fingertips, or your own planetarium."

Christian and her co-developer, Space Telescope Science Institute astronomer Alberto Conti, plan to add the public images from 2007, as well as color images of all of the archived data from Hubble's Advanced Camera for Surveys.

As Ed Parsons, a Google official, noted Sky is a great tool that would be appreciated by users who had the misfortune of living under smog-filled skies. "When was the last time that someone in London could look at the sky and see the stars?" he said. "With this you can see exactly what exists above your home whether you live in New York, Australia or London."

In order to begin your space travel with Sky, all you need to do is to select “Switch to Sky” from the “view” drop-down menu in Google Earth. Form here you can select an object or a category and you will first get a view of the sky showing the constellations surrounding your selected object. As you zoom in, the constellations disappear and your chosen object emerges from the background.

The Sky service will be available on all Google Earth domains, in 13 languages from Wednesday. Users will need to download the newest version of Google Earth which can be found at www.earth.google.com.

Google Earth is a free-of-charge, downloadable virtual globe program. It maps the earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS over a 3D globe. Google Earth was developed by Keyhole, Inc., a company acquired by Google in 2004. The product was renamed Google Earth in 2005 and is currently available for use on personal computers running Microsoft Windows 2000 or XP, Mac OS X 10.3.9 and above, Linux (released on June 12, 2006), and FreeBSD.

Thanks to its collaboration with NASA Google has already launched, Google Mars and Google Moon, two projects similar to Google Earth.