Abstract: Spheres is a A Java package for doing spherical trigonometry without all the messy (and cpu intensive) trigonometry. The spheres package includes classes for points, spherical polygons, latitude/longitude bounding boxes, orbits, and scenes. Spheres documentation includes a variety of algorithm descriptions for performing areal comparisons on the ... sphere.
The spheres package itself performs areal comparisons on the sphere for spherical polygons, lat/lon bounding boxes, orbits, and scenes. At the moment the package is incomplete and not fully tested, except for the parts we're actually using. The javadoc documentation is on-line to give you an idea of what it does, or should do. The source code and the class files are also available in separate jar files (right click and "save as"). Or, if you're really keen, there's everything in one big jar file.