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)
https://hermetic.ch/cal_stud/jdn.htm
Peter Meyer's detailed reference article explains the Julian Day Number system, covering its origins, astronomical vs. chronological uses, and various related date formats like Modified Julian Day Numbers and Lilian Day Numbers. The page includes conversion algorithms and links to calendar software tools, making it a thorough technical reference for astronomers, historians, and calendricists.
http://webmineral.com/
Webmineral is a comprehensive mineralogy database created by David Barthelmy, cataloging 4,714 individual mineral species with detailed descriptions, crystal structure viewers, X-ray data, chemical formulas, and an extensive image library. Its interactive Java-powered crystal viewers, searchable indexes across dozens of physical and optical properties, and multi-language support make it an invaluable reference for geologists, collectors, and mineral enthusiasts alike.
https://www.qsl.net/ctsara
Hosted on QSL.net, this site belongs to CTSARA, likely a Connecticut-area amateur radio association with club resources and member information. The file listing suggests HTML pages with club details and downloadable files, typical of a regional ham radio group's web presence.
https://zl2pd.com/index.html
Andrew Woodfield (ZL2PD) has built an extensive technical resource covering homebrew QRP transceivers, Si5351 VFO/BFO projects, antenna tuners, and DIY electronics for amateur radio operators. The site spans decades of original projects with detailed build guides, circuit diagrams, and modification instructions for portable HF SSB gear.
http://talkorigins.org/faqs/faq-solar.html
Written by Sverker Johansson, this detailed FAQ explores the science of solar neutrinos, nuclear fusion in the sun, helioseismology, and the famous solar neutrino problem with rigorous depth and extensive references. It also addresses creationist arguments about the sun, making it a uniquely thorough resource for both scientific education and skeptical inquiry.
https://qsl.net/kc4gzx/kc4gzx/project.htm
KC4GZX is a sprawling amateur radio and electronics resource by a Georgia ham operator, featuring over 2100 DIY homebrew projects spanning antennas, amplifiers, transmitters, microcontrollers, lasers, and more. It also includes a Northeast Georgia ham directory, repeater listings across multiple southeastern states, and a hamfest schedule, making it an invaluable hub for regional and hobbyist radio enthusiasts.
https://www.qsl.net/dl4tt/DawgX-rayClub.html
The Dawg X-ray Club is a satirical guide for amateur radio operators, humorously skewering the ego-driven behaviors of DXers who chase fame and prestige in the ham radio community. Created by Fritz Sommer (DL4TT), the site features chapters translated into multiple languages and links to classic DX operating resources, blending comedy with genuine community commentary.
http://hamuniverse.com/antennas.html
Hamuniverse.com, run by N4UJW, is a comprehensive ham radio resource site with a dedicated Antenna Design Lab offering hundreds of antenna projects, designs, and build guides for amateur radio operators. Visitors can browse antenna types by band, explore digital modes, study for license exams, and tap into a wide range of technical articles covering everything from repeaters to emergency power.
http://insti.physics.sunysb.edu/physics/physics_links.htm
Maintained by Stony Brook University's physics department, this extensive link directory covers physics preprints, online journals, conferences, jobs, data sources, and institutions. Researchers and students will find hundreds of curated links spanning Physical Review, arXiv, SLAC SPIRES, astrophysics journals, and community resources like Fermilab and the Nobel Foundation.
https://astrotulsa.com/
The Astronomy Club of Tulsa is a non-profit organization that has been bringing astronomy to Oklahoma residents since 1937, operating its own observatory southwest of Tulsa near Mounds and hosting regular public stargazing events. Visitors can find event schedules, monthly newsletters, sky maps, and resources for both beginners and experienced astronomers.