Cornelis "Kees" de Jager is a Dutch astronomer who specializes 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 is a fellow with the Committee for Skeptical Inquiry.
De Jager's current research focuses on predicting solar variation to assess the Sun's impact on future climate. Usually solar activity is defined in terms of the Sun's toroidal magnetic field, the field component parallel to the solar equator. Sunspots are one expression of this component. De Jager introduces the poloidal field of the Sun, which connects its two poles, as a factor of possibly similar importance. He uses proxies for both components and takes 19-year running averages to eliminate all effects that last only one or two solar cycles. Next he plots both components in a diagram, thus creating an experimental phase portrait. The track of the two components went from low to high activity around 1925. Around 2009 the same point has been passed in the opposite direction. 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, thus counteracting global warming. A book, Grand Phases On The Sun: The case for a mechanism responsible for extended solar minima and maxima, was written to outline some of de Jager's research in this regard, along with contributory papers from Bas van Geel and Sylvia Duhau in 2013.
Cyclosophy
Expanding on a 1990 paper presentation at the International Skeptics Conference, de Jager published an article for Skeptical Inquirer where he parodies numerology. In Adventures 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 the Great Pyramids have been used to show a relationship with astronomy. To do so, he explains, anyone can use the law of large numbers to relate to anything one would want, to try and prove there is some connection. As an illustration, he uses the example of his bicycle and the cosmos. Enthusiasts in this formula have created a website that allows visitors to submit data to replicate de Jager's experiment. According to Kendrick Frazier who attended the 1998 Second World Skeptics Congress in Heidelberg, 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.'”
Other activities
He was the General Secretary of the IAU from 1967 to 1973 and former director of the observatory at Utrecht. In 1981, de Jager became a founding member of the World Cultural Council. He was the first chairman of Stichting Skepsis from 1987 to 1998, the first chairman of the European Council of Skeptical Organisations from 1994 to 2001, and is also a Committee for Skeptical Inquiry fellow. de Jager joined his CSI peers by signing the "Deniers are not Skeptics" petition that asks the media to stop referring to climate change deniers as skeptics. He spoke on astrology at the World Skeptics Congress in 1996.
1990 Committee for Skeptical Inquiry In Praise of Reason Award presented de Jager for his "notable contributions to science and his vigorous criticism of pseudoscience."
