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Visualizing the Universe, part I

When I haven't had time (or clear skies) to go observing the actual universe, I've been working on some ways to explore the virtual universe. A few years ago, I designed a basic starchart maker for this site that contains the entire Hipparcos catalog, so it could be used to show the sky from any location within a few hundred light years from Earth. I also found a bunch of stellar velocity data a while back, so for the brighter stars at least, I've been able to run simulations in time as well as space.

By creating a whole bunch of related images, I've created a number of animations illustrating various ideas from amateur astronomy, astrophysics, and even human archaeology and history. I'll begin with a short trip (in time, at least) to the Hyades, the closest large open cluster to Earth, right below the break:

This animation starts at Earth, then proceeds 38 parsecs (125 light years), which is about 85% of the way to the center of the cluster. It then orbits the center of the cluster at a distance of 28 light years, returning back to Earth at the end. You can see that the cluster is roughly spherical, and that some stars that appear very close from Earth really aren't all that close in space.

For the technically curious: I have a copy of this Web site on my system at home. On my home system, there is a customized version of the star chart maker that accepts an HTTP GET request (i.e., all the chart parameters in the query string), and spits out just the image with no surrounding HTML. This isn't available on, since I don't want the server to get hammered. If anyone's interested in a specific animation, please let me know.

For each animation, I have a spreadsheet that contains 1 frame's parameters in each line. It's possible to do some fairly interesting math with simple spreadsheet tools; for example, the distance to and from the Hyades follows a logistic curve instead of being linear with time, and a little trig gives you nice parameters for a circular orbit. After some magic involving Python, Unix shell scripts, ImageMagick, and an occasional chicken sacrifice, this gives me a nice stack of .png image files, one for each line in the spreadsheet, which I can turn into any format I like. In this page, it's Flash (.swf), but I could make an mp4 video or even an animated .gif if I wanted to be really old-school. For this particular animation, I ran this process 3 times (once for the approach, once for the orbit, and once for the return), but with a little spreadsheet macro hacking, I could probably do it with just 1 file.

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