Wednesday, February 02, 2011

Time to switch the screen saver

kw: hobbies, photographs, astronomy, galaxies

You really ought to click on this image to see the larger version (~1,000 px across); this 400 px version is just a bit puny.

I really appreciate the many observatories, including the space ones, that post large, high-resolution images on their web pages. A number of "wallpaper" web sites also post lovely images in their Nature sections. I downloaded these images and others for a specific purpose (my enjoyment), and cropped or resized them to the same dimensions in a 1.6:1 format.

I recently decided it was time to go for a new look with my screen saver. I like the "My Pictures Slideshow" supplied by Microsoft, and I have several folders that I switch among from time to time. For several months I've been showing pictures of various mineral specimens, some that I took of my own minerals, and some downloaded from museum and rock store web sites. Now that I've been classifying galaxies for several weeks in Galaxy Zoo, I decided to show some galaxies that are close enough to home (all less than half a billion light years) to make good subjects for "astro cheesecake".

Although spiral galaxies are the most interesting from a visual perspective, most galaxies are elliptical, such as the first thumbnail in the second row above. Galaxy clusters are typically dominated by one giant elliptical galaxy that is busy consuming its neighboring galaxies, and heavily populated by medium-sized to small elliptical galaxies. About 40% are spirals. The Local Group that includes The Galaxy, the Milky Way where we are, does not have a giant elliptical within it, but contains a number of smaller ones, and only three large spirals, the Milky Way, the Andromeda galaxy M31 and the Triangulum galaxy M33. The Local Group is part of the Virgo Supercluster, which is centered around a pair of giant elliptical galaxies. The fifth and sixth thumbnails in the second row above show central portions of the Virgo Cluster and the Coma Cluster.

When I was a child, I was fascinated by galaxies, and learned to "draw" rather realistic ones on a chalk board by rubbing colored chalk on an eraser and then blowing the dust onto the board. It is quite time consuming. None of these ephemeral artworks was photographed, more's the pity.

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