This learn node focus: To keep up with what is known about our home in the cosmos, the Milky Way Galaxy, online knowledge clusters provide authoritative, up-to-date information and images. The images above are from Sloan Digital Survey, and collaboration of cluster of over 150 scientists and 25 institutions. A December 2007 SDSS news release describes the discovery that The Milky Way has a double halo, as illustrated in the drawing on the left side above. The image on the right of the theoretical model galaxy is from a January 2008 announcement of continuing SDSS surveys studying dark energy, the Milky Way galaxy and giant planets.

There are many excellent Milky Way nodes of knowledge in the open Internet. Galaxy Map, a Web site that is the work of a single expert, has a node on Our Home Galaxy with rich details. Astronomy Picture of the Day has many Milky Way images, including, for example, on on The Milky Way Near the Southern Cross.

And how do we know we live in something called a galaxy and where did our home get its name? Rice University’s Galileo Project explains:

Galileo thought that what had previously been seen as a milky luster in the sky was no more than than these invisible stars. The Milky Way then was just the view of these far distant stars from earth. Nebulae or nebulous stars were in fact actually a number of small stars clustered together. Galileo went on to prove this assertion by sketching out two “nebulae” which were indeed clusters of stars.

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The small section where these maps head up the home page of the PCL Map Collection is a dynamic node for learning provided by the University of Texas Libraries. This week, in addition to subject specific (Bhutto) Pakistan maps, the section provides maps of Afghanistan, Iraq, Sudan, Chad, Darfur, the Turkey/Iraq Border, the US temperature (it is cold!) and tracking, primary, caucus and other political US maps relevant to the Presidential primaries now underway. By keeping this repository of current affairs maps available the UT librarians provide a superb cluster of geography in their corner of the global learning commons.

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