The magnetic field of our planet protects us from many cosmic threats and, for centuries, it has been instrumental in navigation. Decades of studies have unlocked incredible insights into what goes on deep beneath our feet, but there are still new things to consider – such as some peculiar results scientists have been getting.
The magnetic field is not something that is static. The Earth’s magnetosphere is being altered by the solar wind coming from the Sun. During periods of high activity, like now, it is squished more than when the Sun is calmer. These differences have been used to explain why magnetic field observations differ if taken near the Earth’s surface or in space. This was at least the conventional assumption. New work argues that there is more than that at play.
Researchers used data from between 2014 and 2020 since 98.1 percent of the time within that period had geomagnetic conditions of low to moderate. Still, even when the magnetosphere was not being wildly affected by space weather, there were significant differences between observations. In particular, these were more pronounced in the north and south polar regions.
“We often assume a nearly symmetrical magnetic field between the northern and southern polar regions, but they are actually very different,” corresponding author Yining Shi, an assistant research scientist at the University of Michigan Climate and Space Science and Engineering, said in a statement.
Orbital data came from the Swarm satellites, which map currents in the ionosphere, the magnetosphere, and more. They are in polar orbits and this celestial path delivers a lot of measurements around the poles. Many measurements can cause a sampling bias, and when the measurements are inputted into a model that has a simpler view of the magnetic field of our planet, we end up with something that doesn’t match reality anymore.
“Understanding that what has been attributed to geophysical disturbances is really due to the asymmetry of the Earth’s magnetic field will help us better create geomagnetic field models as well as help with satellite and aviation navigation,” said Mark Moldwin, an Arthur F Thurnau Professor of Climate and Space Sciences and Engineering at the University of Michigan and an author on the study.
The polar magnetic field has also been changing rapidly over the last decade. This is an extra challenge that scientists have to face.
“This adds further complexity to creating accurate magnetic field models,” added Moldwin. Having good models is not just important for science, it plays a role in accurate navigation on Earth and in space too.
A paper discussing the results is published in the Journal of Geophysical Research: Space Physics.
Source Link: Earth’s Magnetic Field Is Not The Same At The North And South Poles
