Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson
In the report he submitted to the Académie des Sciences, Poisson imagined a set of concentric spheres at the origin of Earth’s magnetic field. It may come as a surprise to many that Poisson as well as Gauss both considered the magnetic field to be constant. We propose in this study to test this surp...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-07-01
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| Series: | Geosciences |
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| Online Access: | https://www.mdpi.com/2076-3263/13/7/202 |
| _version_ | 1797589124551540736 |
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| author | Jean-Louis Le Mouël Fernando Lopes Vincent Courtillot Dominique Gibert Jean-Baptiste Boulé |
| author_facet | Jean-Louis Le Mouël Fernando Lopes Vincent Courtillot Dominique Gibert Jean-Baptiste Boulé |
| author_sort | Jean-Louis Le Mouël |
| collection | DOAJ |
| description | In the report he submitted to the Académie des Sciences, Poisson imagined a set of concentric spheres at the origin of Earth’s magnetic field. It may come as a surprise to many that Poisson as well as Gauss both considered the magnetic field to be constant. We propose in this study to test this surprising assertion for the first time, evoked by Poisson in 1826. First, we present a development of Maxwell’s equations in the framework of a static electric field and a static magnetic field in order to draw the necessary consequences for the Poisson hypothesis. In a second step, we see if the observations can be in agreement with Poisson. To do so, we choose to compare (1) the polar motion drift and the secular variation of Earth’s magnetic field, (2) the seasonal pseudo-cycles of day length together with those of the sea level recorded by different tide gauges around the globe and those of Earth’s magnetic field recorded in different magnetic observatories. We then propose a mechanism, in the spirit of Poisson, to explain the presence of the 11-year cycle in the magnetic field. We test this mechanism with observations, and finally, we study closely the evolution of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>g</mi><mrow><mn>1</mn><mo>,</mo><mn>0</mn></mrow></msub></semantics></math></inline-formula> coefficient of the International Geomagnetic Reference Field (IGRF) over time. |
| first_indexed | 2024-03-11T01:02:58Z |
| format | Article |
| id | doaj.art-a9f275267ec741f0a80dd902c4ee726c |
| institution | Directory Open Access Journal |
| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-11T01:02:58Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Geosciences |
| spelling | doaj.art-a9f275267ec741f0a80dd902c4ee726c2023-11-18T19:31:50ZengMDPI AGGeosciences2076-32632023-07-0113720210.3390/geosciences13070202Is the Earth’s Magnetic Field a Constant? A Legacy of PoissonJean-Louis Le Mouël0Fernando Lopes1Vincent Courtillot2Dominique Gibert3Jean-Baptiste Boulé4Institut de Physique du Globe de Paris, Université de Paris, 75005 Paris, FranceInstitut de Physique du Globe de Paris, Université de Paris, 75005 Paris, FranceInstitut de Physique du Globe de Paris, Université de Paris, 75005 Paris, FranceLaboratoire de Géologie de Lyon, Terre, Planètes et Environnement, Université de Lyon 1, ENSL, CNRS, UMR 5276, 69622 Lyon, FranceCNRS UMR7196, INSERM U1154, Museum National d’Histoire Naturelle, 75005 Paris, FranceIn the report he submitted to the Académie des Sciences, Poisson imagined a set of concentric spheres at the origin of Earth’s magnetic field. It may come as a surprise to many that Poisson as well as Gauss both considered the magnetic field to be constant. We propose in this study to test this surprising assertion for the first time, evoked by Poisson in 1826. First, we present a development of Maxwell’s equations in the framework of a static electric field and a static magnetic field in order to draw the necessary consequences for the Poisson hypothesis. In a second step, we see if the observations can be in agreement with Poisson. To do so, we choose to compare (1) the polar motion drift and the secular variation of Earth’s magnetic field, (2) the seasonal pseudo-cycles of day length together with those of the sea level recorded by different tide gauges around the globe and those of Earth’s magnetic field recorded in different magnetic observatories. We then propose a mechanism, in the spirit of Poisson, to explain the presence of the 11-year cycle in the magnetic field. We test this mechanism with observations, and finally, we study closely the evolution of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>g</mi><mrow><mn>1</mn><mo>,</mo><mn>0</mn></mrow></msub></semantics></math></inline-formula> coefficient of the International Geomagnetic Reference Field (IGRF) over time.https://www.mdpi.com/2076-3263/13/7/202Poisson theoryEarth’s magnetic fieldconstant intensitylength of daypolar motion |
| spellingShingle | Jean-Louis Le Mouël Fernando Lopes Vincent Courtillot Dominique Gibert Jean-Baptiste Boulé Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson Geosciences Poisson theory Earth’s magnetic field constant intensity length of day polar motion |
| title | Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson |
| title_full | Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson |
| title_fullStr | Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson |
| title_full_unstemmed | Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson |
| title_short | Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson |
| title_sort | is the earth s magnetic field a constant a legacy of poisson |
| topic | Poisson theory Earth’s magnetic field constant intensity length of day polar motion |
| url | https://www.mdpi.com/2076-3263/13/7/202 |
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