42,772 articles
Janka hardness test
The Janka hardness test, also known as the Janka scale, measures wood's resistance to denting by recording the force needed to press a steel ball halfway into the wood.
Janko groups
The Janko groups J₁, J₂, J₃, and J₄ are four of the 26 sporadic finite simple groups, named after mathematician Zvonimir Janko, who found them between 1964 and 1975.
Janna Levin
Janna Levin is a theoretical physicist, the Claire Tow Professor at Barnard College, and author of Black Hole Blues, an account of the campaign to detect gravitational waves.
Jannik Bjerrum
Jannik Bjerrum (1909–1992) was a Danish chemist at the University of Copenhagen whose formation function made stepwise complex formation measurable; his 1941 monograph Metal Ammine Formation in Aqueous Solution became a classic.
Jannik Meyer
Jannik Meyer, also known as Jannik C. Meyer, is a German physicist who studies two-dimensional materials by atomic-resolution electron microscopy and has been a professor at Tübingen since 2018.
János Bolyai
János Bolyai (1802–1860) was a Hungarian mathematician and army officer who independently discovered non-Euclidean geometry, published in 1832 as a 24-page appendix to a textbook by his father, Farkas Bolyai.
János Hajdu
János Hajdu, born 1948 in Budapest, is a Hungarian-born physicist and professor emeritus at Uppsala University known for "diffraction before destruction" X-ray laser imaging and the first imaging of an intact virus with an X-ray laser.
János Kollár
János Kollár, born 1956 in Budapest, Hungary, is a Hungarian-American algebraic geometer and Donner Professor at Princeton University, known for the minimal model program, rationally connected varieties, and moduli theory.
János Komlós (mathematician)
János Komlós, born 1942 in Budapest, is a Hungarian-American mathematician and Distinguished Professor at Rutgers University known for the KMT strong approximation, the AKS sorting network, and the Komlós conjecture in discrepancy theory.
János Szanyi
János Szanyi, also published as Janos Szanyi, is a Hungarian-named American chemist and staff scientist in the Catalysis Science group at Pacific Northwest National Laboratory, known for single-atom catalysis.
Jansen potash mine
Jansen is an underground potash mine under construction in central Saskatchewan, owned by BHP, with first production expected in mid-2027 and a stated investment of CAD$21.8 billion.
Jansky
The jansky (Jy) is a non-SI unit of flux density equal to 10⁻²⁶ W m⁻² Hz⁻¹, used mainly in radio astronomy and named for Karl Guthe Jansky.
Jantar Mantar (जंतर मंतर)
Jantar Mantar (जंतर मंतर), also called Yantra Mandir, is an astronomical observatory in Jaipur, India, built by Sawai Jai Singh II and completed in 1738, with about twenty large masonry instruments used for naked-eye observation.
Jantar Mantar, New Delhi
Jantar Mantar in New Delhi is an 18th-century open-air astronomical observatory built in 1724 by Maharaja Sawai Jai Singh II of Jaipur, the first of his five such observatories.
January 1985 North American cold wave
The January 1985 North American cold wave brought record low temperatures to the Southeastern United States from January 19 to 22, 1985, destroying most of Florida's citrus crop.
January 1998 North American ice storm
The January 1998 North American ice storm, or Great Ice Storm of 1998, coated eastern Ontario and southern Quebec in ice from January 4 to 10, 1998.
January 2016 United States blizzard
The January 2016 United States blizzard, informally Winter Storm Jonas, was a nor'easter that dropped 2 to 3 feet of snow on the Mid-Atlantic, January 22 to 24, 2016.
January 2018 lunar eclipse
The January 2018 lunar eclipse, popularly called the super blue blood moon, was a total lunar eclipse on January 31, 2018, combining a supermoon, a blue moon, and totality.
January 2018 North American blizzard
The January 2018 North American blizzard, or Winter Storm Grayson, was a bomb cyclone that brought blizzard conditions and record coastal flooding to the East Coast.
January 2025 Southern California wildfires
The January 2025 Southern California wildfires were wind-driven fires begun January 7 during strong Santa Ana winds; the Palisades and Eaton Fires destroyed over 16,000 structures.
January 23–27, 2026 North American winter storm
The January 23–27, 2026 North American winter storm, called Winter Storm Fern, brought heavy snow and ice across the United States, killing at least 70 people.
January 30 – February 2, 2026 nor'easter
The January 30 – February 2, 2026 nor'easter, also known as Winter Storm Gianna, was a bomb cyclone that brought record snowfall to the Carolinas.
January–February 2026 North American cold wave
The January–February 2026 North American cold wave pushed Arctic air across the United States from January 22, with Winter Storm Fern leaving over 470,000 without power and dozens dead.
Janus MoSSe
Janus molybdenum disulfide selenide (MoSSe) is a two-dimensional semiconductor in the transition metal dichalcogenide family, first synthesized in 2017, whose different sulfur and selenium faces create an electric dipole studied for photovoltaics and spintronics.
Janus particles
Janus particles are micro- or nanoparticles whose surface is divided into two or more regions with distinct chemical or physical properties, named after the two-faced Roman god Janus.
Janus transition metal dichalcogenide
Janus transition metal dichalcogenide monolayers, named for the two-faced Roman god, are 2D semiconductors of form MXY with different chalcogens on each face, giving an intrinsic vertical dipole; MoSSe was first made in 2017.
Janusz Pawliszyn
Janusz Pawliszyn is a Canadian analytical chemist at the University of Waterloo who invented solid-phase microextraction (SPME), a solvent-free sampling technique used in environmental, food, forensic, and clinical analysis.
Janusz S. Wilczynski
Janusz S. Wilczynski is a physicist and optical engineer known for designing optics for semiconductor manufacturing during a career at IBM's Thomas J. Watson Research Center.
Japan Agency for Marine-Earth Science and Technology (海洋研究開発機構)
The Japan Agency for Marine-Earth Science and Technology, known as JAMSTEC, is Japan's national agency for marine and earth sciences, founded in 1971 and headquartered in Yokosuka.
Japan Meteorological Agency
The Japan Meteorological Agency (Kishōchō) is Japan's national weather service under the Ministry of Land, Infrastructure, Transport and Tourism, responsible for forecasts, severe weather warnings, and earthquake, tsunami, and volcano monitoring.