The course follows a storm from the Sun to Earth's doorstep. This is what happens once it arrives: to the magnetic shield, to the air satellites fly through, and to the ground under a power grid. All of it is measured, from the May 2024 storm.
Earth's magnetic field holds the solar wind off, about ten Earth radii out on the daylit side. The harder the wind pushes, the closer that boundary is forced in. Drag the slider through the storm and watch it.
Your call. Weather and TV satellites sit in geostationary orbit, 6.6 Earth radii out, normally deep inside the shield. At the worst hour of this storm, where were they?
A satellite built to live inside the shield is suddenly out in the raw solar wind. Its magnetic compass reads backwards, charged particles build up on its surface, and operators watch it closely until the boundary moves back out. Meanwhile, inside the shield, the energy let in by a southward field drives the current systems behind everything else on this page.
Storm energy ends up as heat in the thin upper atmosphere. Heated air expands upward, so a satellite a few hundred kilometers up finds itself flying through more of it. More air means more drag, and drag means falling. These are the measured altitudes of three spacecraft through the weeks around the storm.
Your call. February 2022. A rocket puts 49 new Starlink satellites into a low parking orbit, 210 km up, where they will climb from. The next day a storm arrives that forecasters rate G1, the mildest level there is. How many of the 49 are lost?
Thirty-eight. At 210 km the air is already thick enough to matter, and the storm thickened it further. The satellites could not climb against the extra drag and burned up within days. A storm's size is not the whole story: where you are when it arrives counts as much. The tracker's Atmosphere view shows today's drag, and the Starlink storm has its own page and replay.
The same storm drives rivers of electric current through the upper air, a hundred kilometers overhead. A current makes a magnetic field, and this one keeps surging. A changing magnetic field pushes current through anything that conducts, including the rock. Long power lines, earthed at both ends, give that current an easier path than the ground does.
In March 1989 this took down the whole power grid of Québec in 92 seconds, and six million people lost power for nine hours. Grid operators now get storm warnings and can reroute power before a storm arrives, which is one of the reasons arrival forecasts matter. The Québec blackout →
The particles let in through the shield run down the field into the polar sky and make the upper air glow. That is the aurora. The stronger the storm, the further from the poles it reaches: in May 2024 it was photographed from Mexico and northern India. Module 6 shows where the oval is right now, and the aurora page answers for your own city.