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://vkham.com/
VKHam is a comprehensive Australian amateur radio resource hub run by VK2CA, featuring over 12,000 QSL card images, a directory of 1800+ VK callsigns, repeater maps for all Australian states, and DX information. The site also offers kit and radio manuals, electronics resources, frequency tables, and a classifieds section specifically for the Australian ham radio community.
http://math.ucdavis.edu/~calculus
Calculus.org is a comprehensive educational hub hosted by UC Davis, offering step-by-step calculus problems, Java applets, Maple and Mathematica animations, and sample exams for both students and instructors. The site covers differential, integral, and multivariable calculus with resources ranging from humorous beginner guides to actuarial review problems, making it a well-rounded reference for anyone tackling the subject.
http://seboldt.net/k0jd
K0JD's Ham Homebrew Site is a personal amateur radio page by the operator behind the callsign K0JD, focused on homebrewing radio equipment and DIY ham radio projects. The frames-based layout is a classic hallmark of old-web personal pages dedicated to the ham radio hobby.
https://www.qsl.net/mara/index.html
The Madison Area Repeater Association (MARA) is a non-profit amateur radio club based in Madison, Wisconsin, affiliated with the Wisconsin Association of Repeaters. This page serves as a hub for club members, listing meeting times and locations while redirecting visitors to their newer site.
http://company7.com/
Company Seven is a long-established astro-optics retailer and resource hub based in Laurel, Maryland, serving both amateur and professional astronomers with telescopes, binoculars, rare optical instruments, and expert consultation. Notable for its involvement with NASA missions including the Hubble Space Telescope Repair and the James Webb Space Telescope, this site blends a brick-and-mortar showroom presence with a deep online resource for the astronomy community.
http://jgiesen.de/astro/english.htm
Created by J. Giesen, this rich astronomy resource features interactive Java applets for computing solar and lunar positions, planetary visibility, eclipses, sunrise/sunset tables, and much more. Standout features include a top-rated GeoAstro Applet Collection, detailed coverage of the Venus transits and Mars oppositions, and tutorials on astrophysics topics like stellar formation and the Saros cycle.
https://nic.funet.fi/pub/astro/html/astro-uk.html
Hosted on the Finnish University and Research Network (FUNET), this is the national homepage for amateur astronomy in Finland, maintained by members of the Ursa Astronomical Association. It organizes links to Finnish astronomical clubs, research institutions, schools, planetaria, publications, and observation resources, reflecting a country with one of the highest per-capita rates of amateur astronomers in the world.
https://www.qsl.net/ecara
ECARA appears to be an amateur radio club or organization hosted on QSL.net, the well-known hosting platform dedicated to ham radio operators and groups. The directory index suggests a collection of club files and resources, likely including meeting info, member details, or radio-related documents.
https://www.saao.ac.za/~wpk/astron.html
A comprehensive curated directory of astronomy links collected from mailing lists like ASTRO and HASTRO-L, covering everything from beginner stargazing tips to telescope making, satellite tracking, and the history of ancient calendars. Hosted on the South African Astronomical Observatory domain, this resource spans hundreds of links organized into detailed categories for amateur and serious astronomers alike.
https://www2.math.uconn.edu/~glaz/Fun_Math_Links/index.html
Maintained by University of Connecticut math professor Sarah Glaz, this curated link collection gathers hundreds of resources covering math humor, mathematical poetry, math in film and theater, interactive geometry, famous problems, and career guidance. It serves as a rich undergraduate reference bridging serious mathematics with its cultural and creative dimensions.