John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
The otherworldly event is forecast to arrive from a “solar sector boundary crossing.”
Even if it takes gluing your eyelids open, it might be worth staying up late this weekend to catch a glimpse of the aurora borealis in the northern U.S.
On April 29th or 30th, Earth will cross a fold in the heliospheric current sheet—a vast wavy structure in interplanetary space separating regions of opposite magnetic polarity. This is called a “solar sector boundary crossing,” and it could trigger geomagnetic activity around Earth’s poles. NOAA forecasters estimate a 40% chance of G1-class geomagnetic storms on April 29th.
Auroras might flare above Minnesota, North Dakota, Montana, Alaska, and possibly elsewhere, to judge from the Space Weather Prediction Center’s map shown above. (Look for the green line.) As the event approaches, check the center’s regularly updated forecasts for possible viewing locations.