Google Sky


This is a short, but fairly thorough introduction to Google Sky.

To start using NRAO Radio Skymarks, see the GoogleSkyBrochure.

What is Google Sky?

Google Sky is a part of the Google Earth application and allows users to omnisciently explore the universe with a computer connected to the internet. It's like a personal planetarium.

Google Sky was announced on 22 Aug 2007.

What is Google Earth?

Google Earth is a cross-platform desktop application which allows users via internet to see virtually any place on earth, drawing from sources of satellite images, maps, terrain data, and 3D models. It now includes a sky view to allow users to explore the universe in similar fashion; this is Google Sky.

Formerly known as Earth Viewer, the product became part of the Google family in 2004 after Google acquired Keyhole, Inc. in 2004, renaming it to Google Earth in 2005.

Who's Involved in Google Sky?

For starters: Google, but the project has partners in the science community.

Partners listed on the Google Earth/Sky webpage (as of 20 Dec 2007):

A history from Wikipedia (as of 20 Dec 2007):

    " In version 4.2, released August 22, 2007, Google Earth added a Sky tool for viewing stars and astronomical images.[9] Google Sky is produced by Google through a partnership with the Space Telescope Science Institute in Baltimore, the science operations center for Hubble. Dr. Alberto Conti and his co-developer Dr. Carol Christian of the Space Telescope Science Institute, plan to add the public images from 2007,[10] as well as color images of all of the archived data from Hubble's Advanced Camera for Surveys. Newly released Hubble pictures will be added to the Google Sky program as soon as they are issued. New features such as multi-wavelength data, positions of major satellites and their orbits as well as educational resources will be provided to the Google Earth community and also through Christian and Conti's website for Sky. Also visible on Sky mode are constellations, stars, galaxies and animations depicting the planets in their orbits. A real-time Google Sky mashup of recent astronomical transients, using the VOEvent protocol, is being provided by the VOEventNet collaboration. "

Show Me More!

Here are some quick images and a video giving a glimpse of Google Sky. For the full experience, download and run Google Earth.

Online Demo

Screenshots (from the Google blog):

Google Blog Shot1

Google Blog Shot2

Google Blog Shot3

Video demo (from Google Earth's webpage):

Get Google Earth (incl. Google Sky)

Available for PC, Mac, or Linux:

Getting Involved

Google Earth has for some time now allowed users to provide bookmark-like files (called Placemarks) for linking to locations and possibly embedding images into the application. Anyone can create these files for the Google Earth application; for example, visit, a website collecting Google Earth bookmarks/placemarks (format = kmz).

The NRAO can start getting involved with Google Sky by publishing skymarks (officially, these are known as Placemarks, but this is the sky after all) -- bookmarks for Google Sky pointing to a sky location showing an image captured using NRAO telescopes. These skymarks can reside on NRAO web services for users to access -- with possiblities for subscription and notification of newly published skymarks.

Once the NRAO has a collection of skymarks, these can be presented for further integration with the Google Sky application or even for proposal to integrate them as an official part of the Google Sky application.

Technical Details

At the center of adding content to Google Earth is the Placemark. These are provided as mark-up textfiles in the Keyhole Markup Language format, an extension of XML. These files provide meta-data including (but not limited to) location, linked overlay images, and description. KML allows for embedded HTML to provide rich formatting to the description.

Google provides a tutorial to KML at:

There are specifics on Sky Data in KML at:

A KMZ file is a zipped KML file. That is, standard zip tools can unpack a KML file along with related overlay images and icons. The end result? Publish a single file with the Placemark, it's icon, and overlay images; this file is a KMZ file.

Note: this topic is a primer to the Google Earth & Google Sky products. This information is authored by an interested party and is not in any way affiliated with Google. Google and Google Earth are trademarks of Google.

-- RonDuPlain - 20 Dec 2007
Topic revision: r4 - 2008-01-03, RonDuPlain
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