The biggest solar storm since 2011

Written by CNN Staff

This story was originally published on April 16, 2017.

NASA is issuing a geomagnetic storm watch for Halloween, warning of possible high-frequency radio blackouts and increased vulnerability to power outages that may be caused by a massive solar flare that erupted earlier this month.

Sparked by a massive X1.7-class solar flare, the event occurred on February 6 and was the most intense Earth-directed solar flare of the 2016-2017 geomagnetic season. The flare was also the most intense solar storm since 2011.

A day later, a solar phenomenon known as a coronal mass ejection (CME) from the flare ejected a stream of particles at rates up to 200 billion kilometers (125 billion miles) per hour into space. This is known as an “intense solar storm.”

According to NASA, there are two types of a coronal mass ejection: one ejection associated with a CME and one associated with a solar flare.

NASA is watching the highly volatile situation to understand what’s happening and how the particles from the flare impact Earth’s magnetic field.

The solar flare might trigger a coronal mass ejection next month. This burst of particles will be accompanied by “minor geomagnetic disturbance and strong medium-wave radio and telecommunication radio blackouts,” according to NASA.

Severe power blackouts, such as those caused by a failed power grid, might also ensue.

“The main impacts during the northern hemisphere Halloween geomagnetic storm may be radiation for astronauts in orbit and satellites in low-Earth orbit,” NASA said.

Should the worst-case scenario unfold, geomagnetic light shows and thunderstorms are “very likely,” NASA said.

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