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://radiowrench.com/sonic/index.html
A long-running free resource archive started in 1997 offering downloadable manuals, service documents, and technical diagrams for VHF/UHF radios, repeaters, antennas, and related RF equipment. The site hosts PDFs covering everything from GE MVP repeater manuals to tone decoder boards and duplexer specs, making it a valuable reference for amateur radio operators and radio technicians.
https://aurorawatch.lancs.ac.uk/
AuroraWatch UK is a free alert service run by scientists at Lancaster University's Space and Planetary Physics group, notifying users when the aurora borealis might be visible from the UK. The site offers real-time magnetogram plots, activity stackplots, a map, and multi-channel alerts via email, Twitter, Telegram, and more.
http://astronomy.net/
Astronomy.Net is a comprehensive hub for amateur and professional astronomers alike, offering articles, forums, constellation guides, sky event calendars, and equipment classifieds all in one place. Built and maintained by John Huggins since 1994, the site covers everything from telescope optics and astrophotography to meteor showers and planetary conjunctions.
http://calendarzone.com/
The Calendar Zone, created by Janice McLean, is a comprehensive categorized directory of calendar-related links covering art, celestial, cultural, religious, historical, and reform topics. With over 7 million visitors since 1999, it serves as a one-stop hub for anyone curious about calendar systems, moon phases, lunar cycles, and the history of timekeeping across cultures.
http://ham-radio.com/sbms
The San Bernardino Microwave Society (SBMS) is a non-profit technical club dedicated to amateur radio communications above 1 GHz, serving the Southern California region with monthly meetings, contests, and a rich archive of technical papers. Visitors can find member project presentations, contest results for 10 GHz and 2.3 GHz ARRL events, software tools, and newsletters covering cutting-edge microwave experimentation.
https://qrp-labs.com/
QRP Labs sells a wide range of amateur radio kits including multi-band transceivers, CW rigs, GPS receivers, synthesizers, and high-altitude balloon trackers at budget-friendly prices. The site is a go-to destination for QRP radio enthusiasts who enjoy building their own equipment, with kits ranging from beginner-friendly to highly technical designs like the WSPR balloon tracker.
http://thehellhole.com/
A detailed German-language educational site covering black holes and singularities, exploring topics from stellar and supermassive black holes to Hawking radiation, mathematical models, and even the theoretical dangers of black holes at CERN. The site draws a fascinating parallel between modern astrophysics and Norse mythology's concept of the Maelstrom, making complex science accessible through storytelling.
https://k3lr.com/
K3LR is the homepage of Tim Duffy's world-class amateur radio contest station, featuring a multi-operator, multi-transmitter setup that has been featured in QST, RadCom, and the Spectrum Monitor. The site showcases Team K3LR's competition activities, sponsored equipment from Icom and DX Engineering, and links to Dayton Contest University events.
https://lostartoflogarithms.com/
Charles Petzold's web-book-in-progress explores the history, utility, and mechanics of logarithms, from their origins in 400-year-old mathematical tables to slide rules and spherical trigonometry. With over 30 chapter-length pages covering topics like the Book of Vlacq, log-log scales, and John Napier's life, this is a rich and deeply researched labor of love for math history enthusiasts.
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html
Created by Josh Worth, this site presents a scale model of the solar system where the Moon is reduced to a single pixel, requiring visitors to scroll endlessly through vast empty space to appreciate the true distances between planets. The experience is both humbling and educational, with witty commentary along the way and the ability to toggle between kilometers, miles, AU, and other quirky units of measurement.