April 15

Manuel Chrysoloras (c.1355–1415) was a distinguished Byzantine diplomat, philosopher, and professor who introduced classical Greek texts to Western scholars. He taught Greek language and literature in Florence, attracting students such as Leonardo Bruni and influencing the early humanist movement. Chrysoloras translated key works by Homer and other ancient authors into Latin, making them accessible to a broader audience. His efforts bridged Byzantine and Italian intellectual cultures, laying the groundwork for the Renaissance. He also served as a diplomat, negotiating alliances between Byzantium and Western powers before his death in 1415.

Jacopo Francesco Riccati was born in 1676 into a noble Venetian family and developed a passion for mathematics from an early age. His most notable achievement is the general form of the Riccati differential equation, which bears his name and remains fundamental in mathematical analysis. Riccati corresponded with leading scientists of his time, including members of the Royal Society, and held academic positions in Venice and Bologna. He applied his theoretical insights to problems in mechanics and physics, influencing the development of calculus and applied mathematics. Beyond his mathematical work, Riccati was known for his patronage of the arts and letters, embodying the spirit of the Italian Enlightenment. His publications and mentorship helped shape the next generation of European mathematicians. He died in 1754, leaving a lasting contribution to differential equations and scientific thought.

William Oldys was an English antiquarian, bibliographer, and historian who dedicated his life to collecting and cataloguing manuscripts and rare books. Born in London in 1696, he worked as a librarian at the Bodleian Library in Oxford where he organized important collections. Oldys contributed numerous entries to the Biographia Britannica and authored works on the history of English poetry and prose. He was renowned for his meticulous research and deep knowledge of early English writers. His personal library and manuscripts became valuable resources for future scholars. Oldys’s passion for preserving literary heritage influenced the development of literary scholarship in the 18th century.

Peder Horrebow was a Danish astronomer and mathematician born in 1679 in Copenhagen. He succeeded Ole Rømer as professor of astronomy at the University of Copenhagen and continued work on improving astronomical instruments. Horrebow is best known for the 'Horrebow method', a technique to calculate latitude by observing equal altitudes of stars. He compiled precise observations for star catalogues and contributed to refining measurements of the solar system. His research helped advance observational astronomy in the early 18th century. Horrebow's legacy endures in the methods still studied by historians of science.

Mikhail Lomonosov was a towering figure in Russian science and culture, born in 1711 in the Arctic town of Arkhangelsk. He studied in Germany before returning home to revolutionize Russian education and research. Lomonosov formulated the kinetic theory of gases, discovered the atmosphere of Venus, and made significant advances in physical chemistry. He wrote the first Russian grammar and promoted the modernization of the Russian literary language. In 1755, he founded Moscow University, now named in his honor, to train future scientists. His interdisciplinary work laid the groundwork for Russia's scientific development in the centuries to follow.

Ignacije Szentmartony was born in 1718 in Lepoglava, Croatia, and joined the Society of Jesus as a young man. He became a skilled mathematician and astronomer and was selected for a scientific expedition to Brazil from 1753 to 1759. There, Szentmartony conducted extensive geodetic surveys to measure meridian arcs, contributing valuable data to cartography and navigation. He also mapped coastal regions and studied local flora and fauna during his travels. After returning to Europe, he published his findings and taught astronomy at Jesuit institutions. His work bridged scientific exploration and religious scholarship and remains significant in the history of geodesy.

Arthur Aikin, born in 1773 in London, was a prominent chemist, mineralogist, and scientific writer. A founding member of the Geological Society of London, he helped establish geology as a formal discipline. Aikin served as secretary of the British Geological Survey and published important papers on mineral classification and chemical analysis. He also co-edited the Annals of Philosophy, one of the first scientific journals in Britain. His contributions helped disseminate chemical knowledge during the early 19th century. A skilled communicator, Aikin promoted public understanding of science through lectures and educational works.

Born in Ottawa in 1908, John Tuzo Wilson studied geology and geophysics at the University of Toronto and earned his doctorate in 1939. He revolutionized Earth sciences by proposing transform faults and describing the cyclical opening and closing of ocean basins, now known as the Wilson cycle. His mantle plume hypothesis provided a mechanism for volcanic hotspots like Hawaii and Iceland. During his career, he held leadership roles, including presidency of the International Union of Geodesy and Geophysics and of the Royal Society of Canada. Wilson received numerous honors such as the Royal Medal of the Royal Society and the Wollaston Medal of the Geological Society of London. He was a dedicated educator and mentor, shaping future generations of geoscientists. His legacy endures in the fundamental frameworks of modern plate tectonics. He passed away on April 15, 1993, leaving a lasting impact on Earth science.

László Tisza was born in Budapest in 1907 and earned his PhD under Werner Heisenberg before emigrating to the United States in 1939. He became a prominent figure at institutions such as MIT and the University of Chicago, where he explored the properties of superfluids and the foundations of quantum theory. Tisza is celebrated for extending the two-fluid model of superfluidity originally proposed by Lev Landau, providing deeper insight into liquid helium behavior. His research bridged theoretical physics and practical experimentation, influencing generations of physicists. A dedicated educator and author of numerous scholarly articles, he continued to teach and write into his later years, leaving a lasting impact on the field.

Salih Neftçi was born in Istanbul in 1947 and pursued his studies in economics at the London School of Economics and the University of Chicago. He held faculty positions at institutions including the University of Massachusetts Amherst and New York University's Stern School of Business. Neftçi authored seminal texts such as "An Introduction to the Economics of Financial Markets," which remain standard references in finance education. His research advanced the understanding of derivatives pricing, risk management, and market microstructure, earning him recognition as a leader in financial engineering. A respected mentor and speaker, Neftçi shaped the careers of countless economists and practitioners before his passing in 2009.

Benjamin Fain was born in Kherson, Ukraine, in 1930 and moved to Israel in 1972, where he joined the faculty of Tel Aviv University. His research focused on magnetic semiconductors and the electronic properties of crystalline materials, leading to numerous publications in respected journals. Fain was also a dedicated educator, loved by students for his engaging lectures and hands-on approach to teaching complex concepts. He published popular science books aimed at bridging the gap between laboratory research and public understanding of physics. Throughout his career, Fain fostered international collaborations and remained an active speaker at scientific conferences until his death in 2013.

Born in 1919 in Iowa, John Houbolt earned his doctorate in mechanics and hydraulics from the University of Illinois before joining NASA's Langley Research Center. There, he championed the concept of lunar orbit rendezvous (LOR) as a more efficient method for landing astronauts on the Moon. Despite initial resistance within NASA, his persistent proposals convinced decision-makers to adopt LOR for the Apollo program. This strategic choice proved crucial in enabling the first manned Moon landing in 1969. Beyond Apollo, Houbolt contributed to lifting-body research and preliminary designs for the Space Shuttle. After retiring from NASA, he continued to teach and consult, inspiring future generations of aerospace engineers. He died in 2014 at the age of 95, remembered as a visionary in space exploration.