Return Of An Historic Sunspot

It's back. Almost. Sunspot AR3664, the source of the historic May 10th superstorm, has spent the past two week's transiting the farside of the sun. Yesterday, it announced its return with an X2.8-class solar flare. Amateur astronomer Michael Karrer was watching the sun when the explosion occured, and he captured this picture of flying debris:

"I have not seen an explosion like this in my 40 years of observing the sun," says Karrer. "So fast, so far out into space! It was gigantic."

The explosion caused a deep shortwave radio blackout over east Asia and hurled a bright CME into space. A NASA model of the CME confirms that it will miss Mercury, Venus and Earth. None of the inner planets will be affected by this powerful event.

How do we know the flare came from AR3664? Helioseismology. The giant sunspot is affecting the way the sun vibrates, and its seismic echoes are visible in maps of the sun's farside:

This map shows that AR3664 is just behind the southeastern limb of the sun--a good match for the location of yesterday's X-flare. Clearly, AR3664 is still active as it turns to face Earth again later this week.

Source: https://spaceweather.com/