41,000 years ago, a rare extreme event caused cosmic rays to blast through Earth’s magnetic field – report

New research reveals more clues about an extreme event that occurred on Earth 41,000 years ago, when the Earth’s magnetic field temporarily weakened, causing large amounts of cosmic rays to reach the planet.

Recent research could give scientists a deeper understanding of these events and how they might impact our planet if they happened again in the future.

earth cosmic shield

Every day, radiation spreading throughout space bombards our planet’s magnetic field, which acts as a shield against cosmic rays and highly charged particles that are blasted toward our planet from the Sun.

The Earth’s geomagnetic field undergoes periodic changes, including wobbles in magnetic north and occasional reversals of north-south flipping and swapping positions. When this happens, the strength of the planet’s geomagnetic field temporarily decreases.

Rushan incident

Something similar seems to have happened between 42,200 and 41,500 years ago. The magnetic field strength does not reverse permanently, but undergoes a sudden and very drastic change, accompanied by a change of about 45 degrees in the direction of the magnetic poles. Known as the Rashan Event, this represents what scientists call a geomagnetic shift, and it is not only the first known event of its kind, but remains the most widely studied.

During geomagnetic excursions, the resulting low magnetic field strengths result in a reduction in the conventional shielding field against cosmic radiation, which scientists believe could have significant consequences for the Earth and may be related to past recognition of significant changes in Earth’s biosphere.

cosmic ray bombardment

Scientists can determine when greater amounts of cosmic rays bombarded the Earth by measuring radionuclides found in cores extracted from ocean sediments and long-term accumulations of ice. Specifically, isotopes produced by the interaction between our planet’s atmosphere and cosmic radiation can be used as an indicator of the period during which cosmic rays are able to reach Earth.

Researcher Sanja Panovska said the magnetic field strength was significantly affected during the Lachon event, as indicated by the detectable cosmogenic nuclides in the core samples.

Specifically, Panowska said that one particular radionuclide, beryllium-10, provides a good independent proxy for the changes that occurred during Lachamp’s travels, with the average rate of radioisotope production appearing to be twice what it was 41,000 years ago. It’s today.

Combing new data

Although the Laschamp event is the best-studied event of its kind, Panowska’s reconstructions using each data set were able to reveal new information obtained from paleomagnetic data and data related to radionuclides from the origin of the universe.

Based on her reconstruction, Panowska said the Earth’s magnetosphere gradually receded as the geomagnetic field weakened, which she said greatly reduced the amount of shielding from cosmic rays.

Panowska said in the statement that understanding these extreme events is important for their future occurrence, space climate predictions and assessing their impact on the environment and Earth systems.

According to Panowska, the spike in beryllium-10 she found is a good indication that a large number of cosmic rays were able to penetrate our planet’s atmosphere during this extreme event. She will present her findings at the 2024 European Geosciences Union (EGU) Congress.

Micah Hanks is the editor-in-chief and co-founder of The Report. You can contact him via email:micah@thedebrief.org.Follow his workmicahhanks.comOn X:@michahanks.