11-year cycle
The Sun goes through an 11-year solar cycle moving from a period of low activity called solar minimum to a time of heightened activity called solar maximum.
During solar maximum there is an increase in sun spot activity, which are dark patches on the Sun’s surface caused by magnetic field lines breaking through the Sun’s surface.
Because the Sun is not a solid object like the Earth, different parts of it rotate at different speeds, which cause these magnetic field lines to twist and stretch, eventually snapping like elastic bands.
When they snap, they produce an eruption of electromagnetic energy called a solar flare and are sometimes accompanied by a coronal mass ejection (CME).
If directed at Earth, charged particles within the CME slam into the magnetosphere, resulting in the northern and southern auroral lights.
Previous CME events have damaged spacecraft, interfered with communications systems and overloaded ground-based power grids.
Precautions
Despite the potential threat, Dr Wilkinson says authorities are aware of them and are taking precautions.
“We monitor solar activity and issue warnings if something is heading our way,” he said.
“That will be at least a few hours [in advance], enough time to prepare.”
He says while some satellites could be damaged by a future CME, others could be protected by being placed in “safe mode”.
Dr Wilkinson adds the impact on power grids would be minimal.
“At worst, it’s a regional thing, not a global thing as these reports imply,” he said.
He says high frequency communications may also be affected, but it would be temporary.
According to Dr Wilkinson, the Sun has been through a long solar minimum and appears to be heading into a low solar maximum.
Previous observations have shown this could result in high spikes of CME activity.
“It means we could see auroral activity over all of Australia rather than just the higher latitudes,” Dr Wilkinson said.
“It’s unusual, but not unprecedented. James Cook made mention of just such an event off Timor.”
First posted