Boulder, Colorado

The Sun has had the largest number of sunspots in over 20 years this month, according to the US agencies observing the star.

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The estimated Sunspot Number or SNN for 8 August may have reached 299, said the US Space Weather Prediction Center (SWPC) in Boulder, Colorado.

This is the largest number since at least July 2002, it said on its website. These sunspots occurred in a 24-hour period.

The current solar cycle, which is numbered as Solar Cycle 25, "likely reached its highest SSN thus far on August 8, a value of perhaps 299," it said. A solar cycle, estimated to last 11 years, is how the Sun alternates between its so-called solar minimum and solar maximum.

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The official SSN data is released by global agencies in September, though 299 appears to be a possible number. The final number will come from the World Data Center - Sunspot Index and Long-Term Solar Observations (WDC-SILSO).

In fact, the SWPC had recorded the SSN higher at 337, a value not observed since March 2001. 

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What are sun spots?

Each sunspot is the size of the whole earth. These are relatively darker areas on the Sun. 

The rotations of the Sun in each solar cycle lead to areas of magnetic energy on the star. When these areas are very strong, they become visible as sunspots. 

What is the result of sunspots?

Sunspots have strong magnetic fields that cause coronal mass ejections or CMEs. CMEs release large amounts of plasma and magnetic fields from the Sun's corona region. 

These cause solar flares that send out electromagnetic radiation and are experienced as geomagnetic 'solar storms' on Earth.

As sunspots increase, a corresponding rise in solar flares is observed.

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Warnings were issued for geomagnetic storms in the August 11-12 period, around the time when sunspots were estimated at the highest since 2002.

"Solar Cycle 25 is proving to be much more active than originally forecast by the scientist experts who predicted the cycle back in 2019 or so," Space.com quoted Shawn Dahl of SWPC as saying.

The Solar Cycle 25 has already caused intense geomagnetic storms, and auroras on Earth. 

(With inputs from agencies)