Other
Planetary Nebulae Observer Home Page
This home page is linked to detailed descriptions of nebulae types, shapes, and structures and their relationship to stellar evolution, a historical perspective on the discovery of nebulae, a gallery of images, and other related resources.
NASA
Nasa Space Science Data Archive: Comet Fact Sheet
This comet fact sheet, supplied by the NSSDC, provides a table of information on selected comets, complete with commentary when appropriate. Includes details of missions to observe these comets.