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.
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.