Kees de Jager | |
|---|---|
 Kees de Jager in 1967 | |
| Born | Cornelis de Jager (1921-04-29)29 April 1921 |
| Died | 27 May 2021(2021-05-27) (aged 100) Den Burg, Texel, Netherlands |
| Nationality | Dutch |
| Alma mater | Utrecht University |
| Spouse | Doetie Rienks |
| Scientific career | |
| Fields | |
| Institutions | Utrecht University |
| Doctoral advisor | Marcel Minnaert |
Cornelis "Kees"de Jager (pronounced[ˈkeːzdəˈjaːɣər]; 29 April 1921 – 27 May 2021) was a Dutch astronomer who specialized in predictingsolar variation to assess the Sun's impact on future climate. He was the General Secretary of theIAU from 1967 to 1973 and former director of the observatory atUtrecht. He was a fellow with theCommittee for Skeptical Inquiry and played an important role in the Europeanskeptical movement as the first chairman of bothStichting Skepsis and theEuropean Council of Skeptical Organisations.
Born inDen Burg on the Dutch island ofTexel, de Jager spent his school years in theDutch East Indies.[1] 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."[2] From 1939 to 1945, he studiedmathematics,physics andastronomy atUtrecht University.[1][3][4] On 13 October 1952, he obtained hisPhD with a thesis called "The Hydrogen Spectrum of the Sun".[3] His supervisor wasMarcel Minnaert.[4]
De Jager died where he was born, in Den Burg (Texel), on 27 May 2021,[5] less than a month after he became acentenarian.[6][7]
De Jager did work on stars andsolar physics, in relation to which he was a founding editor of the journalSolar Physics.[8] In 1980, he wasprincipal investigator of the Hard X-ray Imaging Spectrometer (HXIS) on board theSolar Maximum Mission satellite.[5] His work onsolar flares was often done in collaboration withZdeněk Švestka.
From 1978 onward, de Jager did noted work on the most luminous stars, known ashypergiants.[9] From 1960 to 1986, de Jager was a professor at Utrecht University.[10][11]
De Jager's later research focused on predictingsolar variation to assess the Sun's impact on future climate.Solar activity is usually defined by the Sun's toroidal magnetic field, the field component parallel to the solar equator. Sunspots are one expression of this component. De Jager introduced thepoloidal field of the Sun, which connects its two poles, as a factor of possibly similar importance. He usedproxies for both components and took 19-yearrunning averages to eliminate all effects that last only one or twosolar cycles.[12][better source needed] Next he plotted both components in a diagram, thus creating an experimentalphase portrait. The track of the two components went from low to high activity around 1923. Around 2006 the same point has been passed in the opposite direction.[13] Thus solar activity in the 21st century is expected to be lower than it was for most of the 20th century. A reduction in solar activity means less energy input to the Earth as part of theEarth's energy budget, partially counteringclimate change.[14]
De Jager postulated that solar magnetic activity is the most significant contributor totropospheric temperatures, with polar activity also being significant, and that with the subtraction of these factors from temperatures recorded over the preceding 400 years, peaks and dips in temperature could be observed, accounting for recent increase in global warming.[13] Similar theories have been rejected by other climate scientists as solar activity and global temperatures have diverged since 1975, with energy output from the Sun decreasing and Earth temperatures still increasing. Additionally, warming caused exclusively by the Sun would result in an even warming throughout the atmosphere, rather than the observed cooling in theupper atmosphere and warming in thelower atmosphere associated withgreenhouse gases.[14]
Expanding on a 1990 paper presentation at the International Skeptics Conference, de Jager published an article forSkeptical Inquirer where he parodiesnumerology. InAdventures in Science and Cyclosophy, de Jager claims that many times pseudoscientific reasoning ignores coincidences dealing with the relationship between objects when there are unlimited data points. He states that measurements surrounding theGreat Pyramids have been used to show a relationship with astronomy. To do so, he explains, anyone can use thelaw of large numbers[15] to relate to anything one would want, to try and prove there is some connection. As an illustration, he uses the example of hisbicycle and the cosmos.[16][17] Enthusiasts in this formula have created a website that allows visitors to submit data to replicate de Jager's experiment.[18]
I measured the diameters of my bike's: -pedals, symbolizing the forward-going dynamics; -front wheel, which directs my ways into the unknown future; -lamp, enlightening my paths; -bell, through which I communicate with encounters. Thus I laid the building stones for a new holistic four-dimensional religion apt to the coming of the New Age of Aquarius: cyclosophy. The measurements were expressed in Holy Bike inches, being 17 mm. This is so since 1 is the first prime number and 17 the seventh, and because seven is the holy number. Calling P, W, L and B the four measured quantities, it turns out that P ^ 2 √ L x W = 1823 which is the ratio between the masses of the proton and the electron.... Coincidences occur regularly in numerical experiments, as in daily life ... are not rare ... Most people greatly underestimate the enormous amount of possible combinations between numbers.Adventures in Science and Cyclosophy[19]
According toKendrick Frazier, who attended the 1998 Second World Skeptics Congress inHeidelberg, Germany, de Jager's "dead-pan" description of how he took measurements throughout his house showing the "absurdities of those who attach great mystical significance to measurements of the Great Pyramid" had the audience "in stitches". Apparently "his home is in an astronomical observatory, a location, he said, 'that may be very close to the cosmos and well receptive to its incredible powers.'"[20]
He was the General Secretary of theIAU from 1967 to 1973 and former director of the observatory atUtrecht.[21] In 1981, de Jager became a founding member of theWorld Cultural Council.[22] He was the first chairman ofStichting Skepsis from 1987 to 1998,[23] the first chairman of theEuropean Council of Skeptical Organisations from 1994 to 2001,[24] and was also aCommittee for Skeptical Inquiry fellow.[25][26]
De Jager joined his CSI peers by signing the "Deniers are not Skeptics" petition that asks the media to stop referring toclimate change deniers as skeptics, with the petition stating "proper skepticism promotes scientific inquiry, critical investigation, and the use of reason in examining controversial and extraordinary claims", not "rejection of ideas without objective consideration".[27]
He spoke on astrology at the World Skeptics Congress in 1996.[28]
In 1969, he became a member of theRoyal Netherlands Academy of Arts and Sciences.[29] In 1990, he was elected a member ofAcademia Europaea.[30]
The asteroid3798 de Jager was named for him.[35]
In 2021, Springer Nature established theKees de Jager Prize in honor of the founding editor of the journalsSolar Physics andSpace Science Reviews as well as the book seriesAstrophysics and Space Science Library. The prize will be awarded annually to the best article in the journalSolar Physics.[36]
