Heavens-Above
heavens-above.com
Predicts when satellites, including the International Space Station, will pass over your location, with sky charts and visibility times.
Why it is useful
Tells you exactly when and where to look to see the ISS and bright satellites pass overhead. A favourite of amateur astronomers and a great one for sharing with children.
More in Hidden Websites
Other hidden websites you might not have heard of.
- Wolfram MathWorldA large mathematics encyclopedia with entries on thousands of topics, from geometry and number theory to topology and probability.
- Nicky CaseNicky Case's portfolio of explorable essays — interactive simulations and games that teach game theory, network effects, cognitive bias, and mental health through systems you can play with and break.
- Gwern.netGwern Branwen's personal research website containing long-form essays, statistical analyses, and experiments on psychology, AI, pharmacology, and prediction.
- Music-MapType in a musician and see a map of similar artists, where closer names are more alike, with links to explore further.
- Marginalia SearchIndependent search engine that deliberately favors non-commercial, text-heavy, and obscure websites.
- SlashdotOne of the internet's oldest tech news and discussion sites, still running — "News for Nerds" since 1997, with a distinctive threaded comment system.