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Biggest solar flare since 2017 could mean the sun is 'waking up’, NASA says

Rob Waugh
The solar flare was detected last week (NASA)

NASA spacecraft just spotted the biggest solar flare since October 2017, from a group of dark sunspots on the other side of the sun.

The change could mean that the sun is beginning to ‘wake up’ after a quiet period – heralding a new period of increased activity.

The flare was spotted on 29 May, blazing from a set of sunspots not yet visible from Earth. 

NASA said: “After months of very few sunspots and little solar activity, scientists and space weather forecasters are keeping their eye on this new cluster to see whether they grow or quickly disappear. 

Read more: The Sun is getting quieter as it hits ‘solar minimum’

“The sunspots may well be harbingers of the sun's solar cycle ramping up and becoming more active.”

Solar flares are powerful bursts of radiation. 

Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground.

Larger solar flares can disturb the atmosphere in the layer where GPS and communications signals travel.

Currently, scientists are paying close attention to the sunspot number as it's key to determining the dates of solar minimum, which is the official start of Solar Cycle 25.

Read more: Spacecraft malfunction as Earth’s magnetic field weakens

This new sunspot activity could be a sign that the sun is possibly revving up to the new cycle and has passed through minimum. 

It takes at least six months of solar observations and sunspot-counting after a minimum to know when it's occurred. 

Because that minimum is defined by the lowest number of sunspots in a cycle, scientists need to see the numbers consistently rising before they can determine when exactly they were at the bottom. 

That means solar minimum is an instance only recognisable in hindsight. It could take six to 12 months after the fact to confirm when minimum has actually passed. 

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