Could a solar storm knock out the internet?

Yes — a severe solar storm could disrupt large parts of the internet, and in an extreme case it could cause major regional or even broader outages. But it’s more accurate to say it could degrade or disable key infrastructure rather than “knock out the internet” outright.

Why:

1. Fiber itself is resilient. Fiber-optic cables carry light, so the cable medium is not very sensitive to electromagnetic interference.
2. Supporting infrastructure is vulnerable. Many long-distance and undersea fiber routes depend on powered electronics such as repeaters/amplifiers, and the power and control systems around them can be affected by geomagnetically induced currents.
3. The electrical grid is a major weak point. A strong geomagnetic storm can damage transformers or trigger widespread power failures, and the internet depends heavily on stable electricity for routers, data centers, cell towers, and home equipment.
4. Satellites can also be affected. Satellite internet, GPS, and some communications links may experience outages, degradation, or increased drag during severe space weather.

So the short answer is: yes, a big enough solar storm could seriously disrupt internet service, especially if it also causes broad power-grid failures. The exact impact would depend on the storm’s strength and which systems are hit.

Space-weather forecasters often provide advance warning for CMEs, but the exact lead time and severity can vary. Because the exact resilience of modern networks is still uncertain, the practical risk is disruption rather than a guaranteed total shutdown.