From the May 2010 issue

Is there any evidence that Earth’s magnetic poles (or any other planet’s) have reversed? What would cause such a reversal?

Gerhard Ligon, Cary, North Carolina
By | Published: May 24, 2010 | Last updated on May 18, 2023
July 2010 Earth's magnetic field
Earth’s magnetic field reverses over a little more than 1,000 years in this simulation. Blue field lines are directed inward, and yellow are directed outward.
Gary Glatzmaier

There certainly is evidence of magnetic dipole reversals of Earth’s magnetic field.