I began by creating a simple search engine to pull up detailed information pages of each star. One could search by name or region of the sky. This was a regular looking database-driven website that took data from a table, let the user search for specific entries and retrieve more information from the table – very standard, and kind of boring. I knew that one could use the GD-library in PHP to generate image files from code, but wasn’t sure how to do it. So, I learned and applied this knowledge by creating star charts in multiple projections based on mathematical transformations of the location data in the database. The first full image I created was a flat projection map of the sky with stellar colors and magnitudes determined by database values. One could clearly make out many of the constellations, as well as the arms of the Milky Way galaxy. Since this was a single image trying to display more than 80,000 stars, it was not very effective, so I placed links on each region to go to a zoomed view. Users could navigate through two additional level of zooming to explore all of the stars in the database. Each star had a link to its detail page as well as title attributes which gave the star’s name. All of these images were dynamically generated using PHP.
From here, I added different projections of the night sky including conical, mercator’s, and molweide’s projections. Each projection took some fairly sophisticated transformations of the polar coordinates to create. I also added a glossary, planet pages, some full text articles, an RSS feed, multimedia and interactive learning objects, a contributor’s interface, and lessons on various topics.
I will be adding posts as time goes on to describe and explain some of the features of the site. These posts will include descriptions of:
- Stellar Mapping — see it in action
- DHTML Gravity Experiment — see it in action
- XML / XSLT / VML Stellar Database — coming soon!
- VRML Saturn V Rocket — coming soon!