Our first story of the day is all about the Sun. This nearest star to Earth both warms our days and periodically kills our spacecraft with its outbursts. While clearly it’s nice to be warm, we like our spacecraft, and figuring out how to better live with our Sun’s weather is the goal of space weather researchers. For 200 years, folks have been finding ways to study the surface of our Sun and its changing starspots, and for nearly 100 years, folks have been finding ways to also study the massive solar flares and coronal mass ejections that we see as vibrant auroras. 

On their own, sunspots are harmless, but those other two events – flares and mass ejections – can include enough high energy particles to affect our high-tech infrastructure. In the past, we’ve seen the power grid in parts of Canada go down as these particles excited our planet’s magnetic field, which in turn drove charge through power lines until they collapsed. We’ve seen satellites get their electronics fried, and we’ve seen historical data that indicates the flares we’ve seen in recent decades are mild compared to some in the past. So how do we predict when these massive flares and ejections are coming? 

According to new work from scientists at the University of Warwick, exact predictions remain impossible – the Sun can generate dangerous weather events at any time – but we now know that the greatest events are likely to occur when the Sun is experiencing what Solar Maxima. Over an eleven-year cycle, the Sun’s magnetic field can invert, and as the field goes from quietly aligned with one of the Sun’s rotational axes to quietly aligned with its other axis, it will go from having virtually no sunspots to being covered in sunspots when that magnetic field is most tangled. That maximum magnetic field chaos and maximum sunspot period is solar max, and it is then that we need to worry. By combining 200 years of sunspot data with 150 years of geologic and other records of geomagnetic storms triggered by the Sun, this team, led by Sandra Chapman, shows that 1-3% of activity occurs during minimum and as the Sun’s activity ramps up, so does the likelihood of bad solar weather. According to Chapman: The ability to estimate the risk of a future solar superstorm occurring is vital for space and ground-based technologies that are particularly sensitive to space weather, such as satellites, communications systems, power distribution, and aviation.

If you have a system sensitive to space weather you need to know how likely a big event is, and it is useful to know when we are in a quiet period as it allows maintenance and other activities that make systems temporarily more fragile.

This is particularly relevant for future plans to put humans on the Moon and send them to Mars. Currently, we don’t have any artificial radiation protection for them, and our best hope will be to send people on these grand explorations when the Sun is most quiet.

More Information

University of Warwick press release 

“Quantifying the Solar Cycle Modulation of Extreme Space Weather,” S. C. Chapman et al., 2020 May 30, Geophysical Research Letters