The Moon’s influence on the Earth’s magnetic field




Greater Copenhagen area

The goal of the project is to study solar and lunar geomagnetic variations in measured time series of magnetic field readings taken at magnetic observatories like Honolulu (Hawai), Hermanus (South Africa) and Kakioka (Japan). By stacking the observations according to solar time and lunar phase both contributions shall be separated and eventually their variation with season and solar activity shall be determined.

More than 95% of the geomagnetic field at Earth’s surface is created by dynamo action in the Earth’s fluid outer core; the remaining few percent are due to magnetized rocks in the Earth’s crust and due to electric currents in the Earth’s ionosphere and magnetosphere. Tidal winds in the ionosphere move a conductor (the ionospheric plasma) through the field lines of the Earth’s magnetic field, which causes electric currents in the ionosphere (“ionospheric dynamo”). These currents cause a magnetic field variation that is measured by geomagnetic stations. The tidal winds (and the corresponding currents and magnetic field variations) consist of a solar component (mainly due to thermal forcing, with heating on the dayside and cooling on the nightside, and a small contribution due to gravitational forcing by the sun) and a lunar component (which is entirely due to gravitational forcing by the moon). The solar contribution is about 20 times larger than the lunar contributions and can be directly seen in the magnetogram of individual days; the lunar contribution is only visible after stacking of data from several months or years of data.

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Company / Organization

DTU Space


Nils Olsen


Professor -afdelingsleder for Geomagnetisme


Supervisor info

BSc in Earth and Space Physics and Engineering


Nils Olsen


Course project

Technical University of Denmark

For almost two centuries DTU, Technical University of Denmark, has been dedicated to fulfilling the vision of H.C. Ørsted – the father of electromagnetism – who founded the university in 1829 to develop and create value using the natural sciences and the technical sciences to benefit society.

Today, DTU is ranked as one of the foremost technical universities in Europe, continues to set new records in the number of publications, and persistently increases and develops our partnerships with industry, and assignments accomplished by DTU’s public sector consultancy.

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