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The sun has ‘gone blank’ as activity hits ‘solar minimum’

No sunspots are visible (SDO/NASA)
No sunspots are visible (SDO/NASA)

Don’t be alarmed, but the sun has just ‘gone blank’ - with recent NASA images showing that the sunspots and flares which speckle the surface have vanished.

The website SpaceWeather.com says, ‘The sun has been without spots for 16 consecutive days, a sign that Solar Minimum is underway.

‘This phase of the solar cycle brings extra cosmic rays and long-lasting holes in the sun’s atmosphere.’

But it’s perfectly normal - part of an 11-year cycle where sunspots regularly fade away, bringing a period of calm.

Dr Tony Philips, space weather expert at Nasa, wrote last month: ‘Sunspots are becoming scarce. Very scarce.

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'So far in 2018, the sun has been blank almost 60 per cent of the time, with whole weeks going by without sunspots. Today’s sun is typical of the featureless solar disk.

Sunspots are strongly magnetised and crackle with solar flares - magnetic explosions which bathe Earth in X-rays and UV radiation.

But over the past couple of years, they’ve been fading - and are sliding towards a low point expected in 2019/20.

‘This is called solar minimum,’ Dean Pesnell of NASA's Goddard Space Flight Center in Greenbelt, MD said last year. ‘And it’s a regular part of the sunspot cycle.’

While intense activity such as sunspots and solar flares subside during solar minimum, that doesn’t mean the sun becomes dull. Solar activity simply changes form.

For instance, says Pesnell, ‘during solar minimum we can see the development of long-lived coronal holes.’

Coronal holes are vast regions in the sun’s atmosphere where the sun’s magnetic field opens up and allows streams of solar particles to escape the sun as the fast solar wind.

Pesnell says ‘We see these holes throughout the solar cycle, but during solar minimum, they can last for a long time - six months or more.’

Streams of solar wind flowing from coronal holes can cause space weather effects near Earth when they hit Earth’s magnetic field.