Readers with long memories might recall that this blog called on Google to turn their powerful mapping technology on the sky. Comments here and in another place showed that we were not alone in wanting to see a Google Universe.

I am happy to say that our prayers have been answered with the launch today of Google Sky.

You will need the very latest version of Google Earth to access it with your PC or Mac. Once installed, switch from the terrestrial to the celestial with a new option under the View menu.

From an intial screen showing the constellations as seen with the naked-eye, users can apparently zoom right in to view more than a million faint stars and 200 million galaxies (I’ve not counted them yet. :-) ).

Google Sky uses images and surveys of the sky from the Hubble space telescope and other major observatories plus institutions including the United Kingdom Astronomy Technology Centre.

Just as with Google Earth, zooming in produces ever increasing levels of detail and objects carry helpful labels. Positions of the Moon and planets are included plus “user’s guides” and advice as to the best targets for stargazers.

At first glance, I felt that the opening screen looked a little crude with its constellation outlines. There were also a few odd artefacts, including a “dandelion clock” at the North Celestial Pole.

Rather bizarrely, placemarkers from Google Earth remained in view when I switched to sky mode. So the Eiffel Tower and Berlin Reichstag were indicated alongside the Whirlpool Galaxy and Messier 94.

But the power of the program becomes clear when you begin to explore it. Close in and be amazed as fainter and fainter stars and galaxies come into view. From a wide-angle view of Ursa Major, I zoomed right in on a star-rich arm of M101, the Pinwheel Galaxy, thanks to clever blending of a Hubble photo, just as one might zoom into one’s street from a starting view of the whole of the UK.

One quirk was that the built-in search failed to show me that well-known star cluser the Seven Sisters, whether I entered its proper name of the Pleiades, Messier 45 or M45. It offered me the “Southern Pleiades”, way down in the southern sky, as an alternative. Never mind. I found the northern original simply enough by scrolling the sky myself.

I am sure that astronomers everywhere will welcome this powerful tool to help anyone who is interested to explore the night sky for themselves. And, of course, they will never need to worry about clouds!

Robin Scagell, vice president of the UK’s Society for Popular Astronomy, told me today: “This sounds very exciting and if it helps people to view the wonders of the heavens, then that is great.

“Hopefully it will also encourage some to take a look at the real sky. After all, as with the Earth, there is a big difference between looking at a picture of the Grand Canyon and actually going there!”

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