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Kees De Jager
Cornelis "Kees" de Jager (; 29 April 1921 – 27 May 2021) was a Dutch astronomer who specialized in predicting solar variation to assess the Sun's impact on future climate. He was the General Secretary of the IAU from 1967 to 1973 and former director of the observatory at Utrecht. He was a fellow with the Committee for Skeptical Inquiry and played an important role in the European skeptical movement as the first chairman of both Stichting Skepsis and the European Council of Skeptical Organisations. Personal life and education Born in Den Burg on the Dutch island of Texel, de Jager spent his school years in the Dutch East Indies. In 1939, De Jager heard Professor Minnaert speak. De Jager said "I was so fascinated by what he said, that I decided right then and there to study Astronomy." From 1939 to 1945, he studied mathematics, physics and astronomy at Utrecht University. On 13 October 1952, he obtained his PhD with a thesis called "The Hydrogen Spectrum of the Sun". His super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Den Burg
Den Burg is a town in the Dutch province of North Holland. It is a part of the municipality of Texel on the island of the same name, and lies about 12 km north of Den Helder. Overview Located in the middle of the island, Den Burg is the largest town of Texel. It features a historic centre and also the town hall. Outdoor markets are held each week in the main square. Nevertheless, Den Burg is the island's least tourist settlement. The town was first mentioned between 918 and 948 as Osterburghem, and means "castle" which refers to a castle built to defend against the Vikings. Notable sites The Dutch Reformed church is a three aisled basilica-like church with 11th century elements. The tower dates from the mid 15th century. After a lightning strike in 1537, it was enlarged. The Oudheidkamer was built in 1599 as guest house and nowadays contains a museum. A monument to the constructed language, Esperanto, is on the corner of Kogerstraat and De Zes. It was constructed in 1935 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trouw
''Trouw'' (; ) is a Dutch daily newspaper appearing in compact size. It was founded in 1943 as an orthodox Protestant underground newspaper during World War II. Since 2009, it has been owned by DPG Media (known as De Persgroep until 2019). ''Trouw'' received the European Newspaper Award in 2012. Cees van der Laan is the current editor-in-chief. History ''Trouw'' is a Dutch word meaning "fidelity", "loyalty", or "allegiance", and is cognate with the English adjective "true". The name was chosen to reflect allegiance and loyalty to God and Country in spite of the German occupation of the Netherlands. ''Trouw'' was started during World War II by members of the Dutch Protestant resistance. Hundreds of people involved in the production and distribution of the newspaper were arrested and killed during the war. The newspaper was published irregularly during the war due to lack of paper. In 1944 the Nazi occupying forces tried to stop publication by rounding up and imprisoning some 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proxy (statistics)
In statistics, a proxy or proxy variable is a variable that is not in itself directly relevant, but that serves in place of an unobservable or immeasurable variable. In order for a variable to be a good proxy, it must have a close correlation, not necessarily linear, with the variable of interest. This correlation might be either positive or negative. Proxy variable must relate to an unobserved variable, must correlate with disturbance, and must not correlate with regressors once the disturbance is controlled for. Examples In social sciences, proxy measurements are often required to stand in for variables that cannot be directly measured. This process of standing in is also known as operationalization. Per-capita gross domestic product (GDP) is often used as a proxy for measures of standard of living or quality of life. Montgomery ''et al.'' examine several proxies used, and point out limitations with each, stating "In poor countries, no single empirical measure can be expected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poloidal
The terms toroidal and poloidal refer to directions relative to a torus of reference. They describe a three-dimensional coordinate system in which the poloidal direction follows a small circular ring around the surface, while the toroidal direction follows a large circular ring around the torus, encircling the central void. The earliest use of these terms cited by the Oxford English Dictionary is by Walter M. Elsasser (1946) in the context of the generation of the Earth's magnetic field by currents in the core, with "toroidal" being parallel to lines of latitude and "poloidal" being in the direction of the magnetic field (i.e. towards the poles). The OED also records the later usage of these terms in the context of toroidally confined plasmas, as encountered in magnetic confinement fusion. In the plasma context, the toroidal direction is the long way around the torus, the corresponding coordinate being denoted by in the slab approximation or or in magnetic coordinates; the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Variation
The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surface. Over the period of a solar cycle, levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation from a period of minimum activity to a period of a maximum activity back to a period of minimum activity. The magnetic field of the Sun flips during each solar cycle, with the flip occurring when the solar cycle is near its maximum. After two solar cycles, the Sun's magnetic field returns to its original state, completing what is known as a Hale cycle. This cycle has been observed for centuries by changes in the Sun's appearance and by terrestrial phenomena such as aurora but was not clearly identified until 1843. Solar activity, driven by b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypergiant
A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae. Origin and definition In 1956, the astronomers Feast and Thackeray used the term ''super-supergiant'' (later changed into hypergiant) for stars with an absolute magnitude brighter than ''M''V = −7 (''M' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zdeněk Švestka
Zdeněk Švestka (30 September 1925 – 2 March 2013) was a Czech astronomer. For several decades he was the world's leading expert on solar flares. He studied mathematics and physics at Charles University, Prague, until graduating in 1948. Together with Cornelis de Jager, he was the co-founder and editor of the journal ''Solar Physics Solar physics is the branch of astrophysics that specializes in the study of the Sun. It deals with detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and compu ...''. For 38 years, from the establishment of the journal in 1967 until his retirement in 2005, he handled all papers on solar flares, while De Jager took care of everything else. The minor planet 17805 Švestka was named after him.Van Driel-Gesztelyi, Lidia"Zdeněk Švestka 1925 - 2013."SolarNews. SolarNews, 15 Mar. 2013. Web. 17 Dec. 2013. References Czech astronomers 2013 deaths 1925 births ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Flare
A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other solar phenomena. The occurrence of solar flares varies with the 11-year solar cycle. Solar flares are thought to occur when stored magnetic energy in the Sun's atmosphere accelerates charged particles in the surrounding plasma. This results in the emission of electromagnetic radiation across the electromagnetic spectrum. High-energy electromagnetic radiation from solar flares is absorbed by the daylight side of Earth's upper atmosphere, in particular the ionosphere, and does not reach the surface. This absorption can temporarily increase the ionization of the ionosphere which may interfere with short-wave radio communication. The prediction of solar flares is an active area of research. Flares also occur on other stars, where the term ''stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Maximum Mission
The Solar Maximum Mission satellite (or SolarMax) was designed to investigate Sun, Solar phenomena, particularly solar flares. It was launched on February 14, 1980. The SMM was the first satellite based on the Multimission Modular Spacecraft bus manufactured by Fairchild Industries, a platform which was later used for Landsat 4, Landsats 4 and Landsat 5, 5 as well as the Upper Atmosphere Research Satellite. After an attitude control failure in Nov 1980 it was put in standby mode until April 1984 when it was repaired by a Shuttle mission. The Solar Maximum Mission ended on December 2, 1989, when the spacecraft Atmospheric reentry, re-entered the atmosphere and burned up over the Indian Ocean. Instruments Failure and repair The white-light coronagraph/polarimeter (C/P) took coronal images for about six months from March 1980 before suffering an electronics failure in September that prevented operation. In November 1980, the second of four fuses in SMM's attitude control system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principal Investigator
In many countries, the term principal investigator (PI) refers to the holder of an independent grant and the lead researcher for the grant project, usually in the sciences, such as a laboratory study or a clinical trial. The phrase is also often used as a synonym for "head of the laboratory" or "research group leader". While the expression is common in the sciences, it is used widely for the person or persons who make final decisions and supervise funding and expenditures on a given research project. A co-investigator (Co-I) assists the principal investigator in the management and leadership of the research project. There may be a number of co-investigators supporting a PI. Federal funding In the context of United States federal funding from agencies such as the National Institutes of Health (NIH) or the National Science Foundation (NSF), the PI is the person who takes direct responsibility for completion of a funded project, directing the research and reporting directly to the fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Physics (journal)
''Solar Physics'' is a Peer review, peer-reviewed scientific journal published monthly by Springer Science+Business Media. The editors-in-chief are Lidia van Driel-Gesztelyi (various affiliations), John Leibacher (National Solar Observatory, and Institut d'astrophysique spatiale, Institut d'Astrophysique Spatiale), Cristina Mandrini (Universidad de Buenos Aires), and Inigo Arregui (Instituto de Astrofísica de Canarias). Scope and history The focus of this journal is fundamental research on the Sun and it covers all aspects of solar physics. Topical coverage includes solar-terrestrial physics and stellar research if it pertains to the focus of this journal. Publishing formats include regular manuscripts, invited reviews, invited memoirs, and topical collections. ''Solar Physics'' was established in 1967 by solar physicists Cornelis de Jager and Zdeněk Švestka, and publisher D. Reidel. Abstracting and indexing This journal is indexed by the following services: * Science Citatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Physics
Solar physics is the branch of astrophysics that specializes in the study of the Sun. It deals with detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and computer science, including fluid dynamics, plasma physics including magnetohydrodynamics, seismology, particle physics, atomic physics, nuclear physics, stellar evolution, space physics, spectroscopy, radiative transfer, applied optics, signal processing, computer vision, computational physics, stellar physics and solar astronomy. Because the Sun is uniquely situated for close-range observing (other stars cannot be resolved with anything like the spatial or temporal resolution that the Sun can), there is a split between the related discipline of observational astrophysics (of distant stars) and observational solar physics. The study of solar physics is also important as it provides a "physical laboratory" for the study of plasma physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
