Astronomy Search Engines:

bullet 4StarGazing - Directory of astronomy, planetarium and star gazing sites.
 
bullet About Astronomy and Space - Guide to space and astronomy resources and information.
 
bullet Astrobiology Web - An online guide to the origin, evolution, and distribution of life in the Universe as well as all
bullet 
bullet Astronomy Net - Directory of astronomy resources, searchable forums and searchable lists of organizations providing astronomy services.
 
bullet Astronomy Resources - Search for educational astronomy information and links in over 50 categories.
 
bullet astronomyLINKS - Astronomy and space directory, links, booksmarks and more.
 
bullet Brian's Space Hotlist - Directory of links to quality space information intelligently organized into a number of topics, and annotations make it clear what each site listed is about.
 
bullet Cosmobrain - Astronomy and astrophysics directory.
 
bullet Galacticsurf - Portal to all those who are nuts about space sciences: from the infinitly small (particle physics) to the infinitly big (cosmology).
 
bullet Links to Astronomy - Drennon's Astronomy guide with current information on astronomical events and the science of astronomy.
 
bullet LiveSky - Astronomy search engine. Search NASA archives, Internet web pages, astronomy usegroups, and astronomical databases for the information you need.
 
bullet SpaceBOX - Astronomy resources directory.
 
bullet SpaceRef - Space directory and search engine. Includes space exploration and missions, a space calendar of events, and interactive space news.
 
bullet Top 20 Astronomy - Online directory for astronomy education including solar systems, galxies, cosmology, astrophysics, radio, organizations, and more.
 

Earth Sciences Search Engines:

bullet Athena Earth Sciences Resources - Directory of earth sciences resources.
 
bullet columbia earthscape - Selects, gathers, edits, and links to Earth resources available online.
 
bullet GEOindex - Carefully selected and categorized links specific to the Geo-Environmental Industry.
 
bullet Geologia - Geology and nature. Earth science on the net.
 
bullet GeoSearch - Geology and rockhound search engine.
 
bullet  Geosource - Directory of resources for human geography, physical geography, planning, geoscience and environmental science. Provided by Utrecht University Library.
 
bullet Links for Mineralogists - Annotated links to internet resources, especially for mineralogists, petrologists, crystallographers, geologists.
 
bullet Links to Earth-Science Resources - A commented list of links to a selection of the best Earth-Science resources on the Internet.
 
bullet NASA's Global Change Master Directory - Directory of information about Earth science data, including a broad coverage of global warming, the oceans, atmosphere, hydrosphere, solid earth, biosphere and human dimensions of global change.
 
bullet UMass Lowell Weather Links Directory - Provided by the Department of Earth, Environmental and Atmospheric Sciences Meteorology Program, University of Massachusetts-Lowell.
 
bullet WindandSea - Selected links to science and policy sites organized by topic and alphabetically within topic. All of these sites have been reviewed and annotated by a technical information specialist of the NOAA Central Library staff.
 

Ecology Search Engines:

bullet Ecology WWW Page - Directory of ecology related resources.
 
bullet WWW Virtual Library: Ecology and Biodiversity - The Virtual Library of Ecology and Biodiversity division of The Virtual Library Project specializes in reviewing internet information sources pertaining to ecology and biodiversity based on their educational value.