科学技术类搜索引擎及目录索引

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天文学 Astronomy：

4StarGazing - Directory of astronomy, planetarium and star gazing sites.

Astronomical Links

Astronomy Links

Astronomy Net - Directory of astronomy resources, searchable forums and searchable lists of organizations providing astronomy services.

Astrosights.com - The web directory designed for amateur astronomers.

Expanding Universe - Search tool for amateur astronomy.

German Astronomical Directory

LiveSky - Astronomy search engine. Search NASA archives, Internet web pages, astronomy usegroups, and astronomical databases for the information you need.

Planet S - Search engine for astronomy, space, and physic web sites.