The sun’s magnetic north and south magnetic poles are expected to reverse over the next few months. We’ve witnessed only a few such reversals and are not entirely sure what effects they may cause. Read more for an explanation of what we do know about solar and terrestrial magnetic field reversals.
We’ve just passed the northern autumn equinox when the length of the night begins to overtake the length of the day. During this transition, the sun rises due east and sets due west and geosynchronous satellites lose solar power for part of their orbit as the earth eclipses the sun.
For unknown reasons, displays of northern and southern lights (Aurora Borealis and Aurora Australis) tend to occur more often during the equinoxes.
At this time of the year, the earth’s equator is parallel to the plane of the earth’s orbit. The sun’s north pole is on the left side of the rising sun and on the right side of the setting sun. Like the earth’s magnetic pole, the sun’s magnetic pole isn’t perfectly aligned with its spin axis and its magnetic field has a complex shape and is subject to unpredictable changes and pulsations.
The earth’s magnetic field is thought to be caused by the electric currents generated by the movement of molten iron and other metals in the earth’s core. The sun’s magnetic field comes from the movement of conductive plasma within the sun’s interior. Because the conductive fluid dynamos which power these magnetic fields are chaotic, both the sun and the earth are subject to occasional magnetic pole reversals.
Earth magnetic field reverses only about once every 200,000 to 300,000 years. It is thought that when earth’s magnetic field weakens during these geomagnetic flips, earth is exposed to higher levels of cosmic radiation. We’re long overdue for such a reversal, so it is expected within the next 2000 years.
The sun’s magnetic field reverses much more frequently by comparison, about once every 11 years during the peak of each solar activity cycle. Fortunately, scientists expect only minor effects from a solar magnetic flip.
Geomagnetic storms which can impact telecommunications and spark aurora displays might be slightly more common during solar magnetic pole flips. But we’ve been tracking the solar magnetic field since 1976. The sun may surprise us during its fourth observed magnetic pole flip. Keep an eye on spaceweather.com for more details.
Solar corona image with magnetic fields from the atmospheric imaging assembly website.