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🔗 Cryptography 🔗 Cryptography/Computer science

The Cardan grille is a method of writing secret messages using a grid.

🔗 Astronomy 🔗 Astronomy/Astronomical objects

2024 YR₄ is an asteroid between 40 and 90 metres (130 and 300 ft) in diameter, classified as an Apollo-type (Earth-crossing) near-Earth object. It was discovered by the Chilean station of the Asteroid Terrestrial-impact Last Alert System (ATLAS) on 27 December 2024. As of 5 February 2025, 2024 YR₄ was rated 3 on the Torino scale with a 1 in 53 (1.9%) chance of impacting Earth on 22 December 2032. NASA gives a Palermo Technical Impact Hazard Scale rating of −0.40 for 2024 YR₄, which corresponds to an impact hazard of 39.8% of the background hazard level. The discovery has triggered the first step in planetary defense responses, in which all available telescopes are asked to gather data about the object and United Nations-endorsed space agencies are prompted to begin planning for asteroid threat mitigation.

Preliminary analysis of spectra and photometric timeseries of this asteroid suggests it is a stony S-type or L-type asteroid with a rotation period near 19.5 minutes. The asteroid previously made a close approach of 828,800 kilometres (515,000 miles; 2.156 lunar distances) to Earth on 25 December 2024 (two days before its discovery), and is now moving away from Earth. It will make its next close approach around 17 December 2028. By early April 2025 and until June 2028, 2024 YR₄ will have moved too far away from Earth to be observed by ground-based telescopes. Space-based infrared telescopes such as the James Webb Space Telescope may be able to observe 2024 YR₄ when it is far from Earth.

🔗 Internet culture

Zalgo text, also known as cursed text due to the nature of its use, is digital text that has been modified with numerous combining characters, Unicode symbols used to add diacritics above or below letters, to appear frightening or glitchy.

Named for a 2004 Internet creepypasta story that ascribes it to the influence of an eldritch deity, Zalgo text has become a significant component of many Internet memes, particularly in the "surreal meme" culture. The formatting of Zalgo text also allows it to be used to halt or impair certain computer functions, whether intentionally or not.

🔗 Medicine 🔗 Biology

The blue field entoptic phenomenon is an entoptic phenomenon characterized by the appearance of tiny bright dots (nicknamed blue-sky sprites) moving quickly along undulating pathways in the visual field, especially when looking into bright blue light such as the sky. The dots are short-lived, visible for about one second or less, and traveling short distances along seemingly random, undulating paths. Some of them seem to follow the same path as other dots before them. The dots may appear elongated along the path, like tiny worms. The dots' rate of travel appears to vary in synchrony with the heartbeat: they briefly accelerate at each beat. The dots appear in the central field of view, within 15 degrees from the fixation point. The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances. While seeing the phenomenon, lightly pressing inward on the sides of the eyeballs at the lateral canthus causes the movement to stop being fluid and the dots to move only when the heart beats.

Most people are able to see this phenomenon in the sky, although it is relatively weak in most instances; many will not notice it until asked to pay attention. The dots are highly conspicuous against any monochromatic blue background of a wavelength of around 430 nm in place of the sky. The phenomenon is also known as Scheerer's phenomenon, after the German ophthalmologist Richard Scheerer, who first drew clinical attention to it in 1924.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Guild of Copy Editors 🔗 Linux 🔗 Computing/Early computers

Emacs or EMACS (Editor MACroS) is a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, self-documenting, real-time display editor". Development of the first Emacs began in the mid-1970s, and work on its direct descendant, GNU Emacs, continues actively as of 2020.

Emacs has over 10,000 built-in commands and its user interface allows the user to combine these commands into macros to automate work. Implementations of Emacs typically feature a dialect of the Lisp programming language that provides a deep extension capability, allowing users and developers to write new commands and applications for the editor. Extensions have been written to manage email, files, outlines, and RSS feeds, as well as clones of ELIZA, Pong, Conway's Life, Snake and Tetris.

The original EMACS was written in 1976 by Carl Mikkelsen, David A. Moon and Guy L. Steele Jr. as a set of Editor MACroS for the TECO editor. It was inspired by the ideas of the TECO-macro editors TECMAC and TMACS.

The most popular, and most ported, version of Emacs is GNU Emacs, which was created by Richard Stallman for the GNU Project. XEmacs is a variant that branched from GNU Emacs in 1991. GNU Emacs and XEmacs use similar Lisp dialects and are for the most part compatible with each other.

Emacs is, along with vi, one of the two main contenders in the traditional editor wars of Unix culture. Emacs is among the oldest free and open source projects still under development.

🔗 Spaceflight

NASA Extreme Environment Mission Operations, or NEEMO, is a NASA analog mission that sends groups of astronauts, engineers and scientists to live in Aquarius underwater laboratory, the world's only undersea research station, for up to three weeks at a time in preparation for future space exploration.

Aquarius is an underwater habitat 3.5 miles (5.6 km) off Key Largo, Florida, in the Florida Keys National Marine Sanctuary. It is deployed on the ocean floor next to deep coral reefs 62 feet (19 m) below the surface.

NASA has used it since 2001 for a series of space exploration simulation missions, usually lasting 7 to 14 days, with space research mainly conducted by international astronauts. The mission had cost about 500 million U.S. dollars. The crew members are called aquanauts (as they live underwater at depth pressure for a period equal to or greater than 24 continuous hours without returning to the surface), and they perform EVAs in the underwater environment. A technique known as saturation diving allows the aquanauts to live and work underwater for days or weeks at a time. After twenty four hours underwater at any depth, the human body becomes saturated with dissolved gas. With saturation diving, divers can accurately predict exactly how much time they need to decompress before returning to the surface. This information limits the risk of decompression sickness. By living in the Aquarius habitat and working at the same depth on the ocean floor, NEEMO crews are able to remain underwater for the duration of their mission.

For NASA, the Aquarius habitat and its surroundings provide a convincing analog for space exploration. Much like space, the undersea world is a hostile, alien place for humans to live. NEEMO crew members experience some of the same challenges there that they would on a distant asteroid, planet (i.e. Mars) or Moon. During NEEMO missions, the aquanauts are able to simulate living on a spacecraft and test spacewalk techniques for future space missions. Working in space and underwater environments requires extensive planning and sophisticated equipment. The underwater condition has the additional benefit of allowing NASA to "weight" the aquanauts to simulate different gravity environments.

Until 2012, Aquarius was owned by the National Oceanic and Atmospheric Administration (NOAA) and operated by the National Undersea Research Center (NURC) at the University of North Carolina–Wilmington as a marine biology study base.

Since 2013, Aquarius is owned by Florida International University (FIU). As part of the FIU Marine Education and Research Initiative, the Medina Aquarius Program is dedicated to the study and preservation of marine ecosystems worldwide and is enhancing the scope and impact of FIU on research, educational outreach, technology development, and professional training. At the heart of the program is the Aquarius Reef Base.

🔗 Physics 🔗 New Zealand 🔗 Physics/History

The Beverly Clock is a clock situated in the 3rd floor lift foyer of the Department of Physics at the University of Otago, Dunedin, New Zealand. The clock is still running despite never having been manually wound since its construction in 1864 by Arthur Beverly.

🔗 Philosophy 🔗 Skepticism 🔗 Classical Greece and Rome 🔗 Greece 🔗 Philosophy/Ancient philosophy

A sophist (Greek: σοφιστής, romanized: sophistēs) was a professional travelling teacher in ancient Greece in the fifth and fourth centuries BC. Sophists specialized in one or more subject areas, such as philosophy, rhetoric, music, athletics, mathematics, and arete: "virtue" or "excellence". The sophists sold their tutoring expertise predominantly to young statesmen and nobility. Certain sophists are regarded as philosophers in their own right. The first credited sophist, Protagoras, argued that "man is the measure of all things", and he controversially would strive to "make the weaker argument the stronger".

The arts of the sophists were known as sophistry and gained a negative reputation as arbitrary, inauthentic, or deceptive styles of reasoning, beginning with the notable philosophers of Classical Athens who criticized sophists for valuing artistic speech or cleverness in debate over a genuine pursuit of truth and knowledge. Thus, in modern usage, sophism, sophist, and sophistry are used disparagingly. Sophistry, or a sophism, is a fallacious argument, especially one used deliberately to deceive. Today, a sophist is a person who reasons with clever but deceptive or intellectually dishonest arguments.

🔗 Netherlands 🔗 Highways 🔗 Caribbean 🔗 Highways/Road transport 🔗 Caribbean/Caribbean Netherlands 🔗 Highways/Latin American Highways

The Road is the unofficial name for the cement road that connects the villages of Saba, Netherlands, a Caribbean island. It is nicknamed "The Road That Couldn't Be Built". It is the primary road on the island, spanning 8.7 miles (14.0 km). It was constructed by local Sabans between 1938 and 1963, without the use of machines.