Fourmilab
fourmilab.ch
John Walker's long-running site with essays, software and tools, including the well-known Earth and Moon viewers that show the day and night sides of the planet.
Why it is useful
A classic corner of the web with an unusual mix of science, history and software, much of it free to use. The Earth viewer is a beautiful way to see where it is day and night right now.
More in Hidden Websites
Other hidden websites you might not have heard of.
- Farnam StreetShane Parrish's site on mental models, decision-making, and thinking clearly — drawing from business, psychology, philosophy, and history.
- ShorpyA blog of high-resolution historical photographs, mostly from the United States, each one posted with a caption and a lively comments section.
- Information Is BeautifulDavid McCandless's collection of data visualisations and infographics, which turn complicated facts and numbers into clear, striking images.
- Bored ButtonPress a button to be sent to a random, curated, interesting website from across the internet.
- TinEyeReverse image search engine that finds where an image appears online.
- How Normal Am IAn interactive essay that uses your webcam and on-device ML to analyze your face — estimating your age, attractiveness, BMI, and emotional state to reveal how these algorithms work and what assumptions they encode.