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What is a geomagnetic storm? Will auroras be visible in the United States?

The National Oceanic and Atmospheric Administration (NOAA) released an alert for 26 April that auroras may be visible from Northern US states.

What is a geomagnetic storm? Will auroras be visible in the United States?

Geomagnetic storms occur when solar winds exchange energy with the space surrounding the earth. When radiation from a large solar flare penetrates the ionosphere and the other upper levels of the earth’s atmosphere, these unique meteorological events can create auroras or the “northern lights.”

The radiation released from the solar flares that interact with various parts of the earth’s atmosphere takes four or five days to arrive. The interactions with multiple elements cause the different colors to appear in the sky. For example, nitrogen atoms tend to create reddish light while oxygen makes more green light.

How and where to watch the storm?

National Oceanic and Atmospheric Administration (NOAA) released an alert for 26 April that auroras caused by a geomagnetic storm may be visible from Michigan, Maine, and other Northern US states. There are a total of five severities used by NOAA to describe geomagnetic events. NOAA has described the alert as ‘Mminor” and does not anticipate any major disruptions. A “Minor” event can cause some issues for

• Spacecraft: Minor impact on satellite operations possible.

• Power systems: Weak power grid fluctuations can occur

On the opposite end of the scale, “Extreme” storms can cause significant disruptions to electrical grids leading to blackouts, and the auroras can be seen in Florida and Texas.

When was the largest geomagnetic storm ever recorded?

The Carrington Event, which occurred September 1st and 2nd, 1859, was the largest geomagnetic storm ever recorded. The two-day event led to auroras being seen in places as south as Cuba, Mexico, and even Colombia. The powerful solar event caused telegraph systems across the United States and Europe to fail, and cases of telegraph operators being shocked were reported. Over 150 years later, in 2013, researchers investigated the event and found that in the United States alone, the damage done during the Carrington Event could have totaled up to $2.6 trillion today. The report also identified the corridor between Washington DC and New York City as the most vulnerable to power outages caused by geomagnetic storms.

Since the Carrington Event, some geomagnetic storms have been able to knock out parts of the power grid in the US, but none have neared the level of devastation seen in 1859.