North Australian FISH FINDER forums

Solar storms (what causes auroras) cause GPS to be wrong, as the plasma affects the signal.

"GPS receivers work with the assumption that the ionosphere has a uniform plasma density," Waqar Younas, a space physics researcher at Boston University and lead author of the paper, told Space.com. "But a solar storm creates irregularities in the ionosphere and as the signal passes through the ionospheric layers, it grows errors."

Significant errors too, more here ... https://www.space.com/astronomy/sun/may ... dy-reveals