Science & Nature
1439 sites
Subcategories:
- Astronomy & Space (396)
- Chemistry (8)
- Earth Sciences (26)
- Biology (79)
- Physics (30)
- Mathematics (59)
- Weather & Climate (104)
- Amateur Radio (682)
- Electronics (47)
http://theastropages.com/
The @stro Pages is a long-running amateur astronomy hub offering astrophotos, articles, telescope making guides, an observer's log, and a San Diego stargazing calendar. Packed with community features like discussion boards, a monthly newsletter, and links to deep-sky objects, it serves both beginners and experienced skywatchers.
http://f5ad.free.fr/
Built by French radio amateur André Ducros (callsign F5AD), this extensive site covers amateur radio antennas, amateur television (ATV), and ham radio licensing with over 616 pages and 2648 images. It includes 1205 practical antenna descriptions ranging from shortwave to microwave, technical documentation, and resources for ATV transmission, making it a remarkable reference archive for French-speaking radio amateurs.
https://metrocor.net/
MetroCor is the Metropolitan Coordination organization for amateur radio repeaters covering New York City, New Jersey, and surrounding counties, maintaining an extensive database of coordinated frequencies across bands from 10 meters through 23 centimeters. The site publishes detailed repeater coordination tables listing hundreds of callsigns, output and input frequencies, PL tones, and coordination status for the greater NYC metro area.
https://pskreporter.info/pskmap.html
PSKReporter is a real-time propagation mapping tool that aggregates reception reports from amateur radio operators worldwide, showing who is hearing whom across bands and digital modes like FT8, JT65, and PSK31. Created by Philip Gladstone, the interactive map lets operators filter signals by callsign, country, grid square, mode, and time window, making it an invaluable tool for monitoring radio propagation conditions.
http://blackcanyonastronomy.com/
The Black Canyon Astronomical Society (BCAS) is an amateur astronomy club serving Western Colorado, offering public meetings, star parties, dark sky preservation efforts, and outreach programs to schools and community groups. The site features a calendar of events, astrophotography gallery, observing highlights, and information on joining the Astronomical League.
https://n3wnb.tripod.com/
Tim Ingram (N3WNB) of Corry, PA built this ham radio page featuring a callsign lookup tool and a curated collection of links to resources like the ARRL, QRZ, and equipment suppliers. The site also highlights his Yaesu FT-847 rig and includes a local hams email list, giving it a personal community flavor alongside the standard reference links.
http://users.netonecom.net/~swordman/Radio/unun.htm
Doug's page details the hands-on construction and testing of an impedance-matching transformer (Unun) for connecting a 350-foot long-wire antenna to a shortwave receiver. Complete with photos of the wound toroid core, schematic references, and bandscanning results comparing performance with and without the transformer, it's a practical reference for anyone building receiving antenna accessories.
http://hf.dxview.org/
Created by NG0E, HF+ is an interactive real-time propagation map that displays current amateur radio band conditions worldwide from 1.8 to 50.4 MHz, showing where contacts are likely based on your operating location. It draws live data from sources like WSPRnet, PSK Reporter, and the Reverse Beacon Network to indicate support for SSB, CW, and digital modes, and even predicts signal levels for the next 24 hours.
http://stellar-database.com/scale.html
A concise educational page from stellar-database.com that walks readers through the mind-bending scale of the universe, from the Earth's diameter out to the edge of the known cosmos. It explains astronomical units, light-years, and parsecs with precise conversion figures, making vast cosmic distances tangible and comparable.
https://plaws.net/
Peter Laws has maintained this personal page since 1994, with amateur radio as its clear centerpiece, including newsletters from the University of Arkansas Amateur Radio Club dating back to 1992 and numerous presentations and videos on topics like satellites, DXLab, and outdoor warning sirens. The site also touches on scanning, trains, and AI, but the depth of ham radio content spanning three decades makes it a genuine archive for radio enthusiasts.