Since mid-January, the Sun has continued its active behaviour with flares and coronal mass ejections appearing almost every day. Thus, some of these eruptions have blasted toward the earth, indicating some solar storms are on their way.
Several weather agencies have issued weather advisories for mild and moderate geomagnetic storms in the upcoming days, including the Space Weather Prediction Center of the US National Oceanic and Atmospheric Administration (NOAA) and the British Met Office.
Dramatic reenactment of a large coronal ejection. Credit: Clintern
However, this does not necessarily mean there is anything to worry about; in fact, over the last few days, we have already been hit by mild and moderate geomagnetic storms that rank between G1 and G2 on a five-level scale.
As a result of the change in drag at high latitudes, this level indicates there may be some degradation of high-frequency radio signals. Corrective actions may be needed for satellites. The power grid may fluctuate and some migratory animals could be disrupted. Satellites can also be knocked out of the sky if the conditions are right.
We may also see an uptick in both aurora borealis and aurora australis.
"There is a chance of enhancements to the auroral oval at times during 13th and 14th March as a result of two Coronal Mass Ejections (CMEs) and a coronal hole high-speed stream arriving at Earth," the British Met Office advised. These light shows may be seen as low as 55 degrees latitude, at each pole.
Whenever our Sun becomes more active, solar storms occur. Therefore, CMEs and solar winds disrupt the Earth's magnetic field and upper atmosphere. Both phenomena are currently occurring.
As the name suggests, CMEs are pretty much what they sound like. Solar coronas erupt, ejecting plasma and magnetic fields into space. As the CME approaches Earth, the solar ejecta may collide with the magnetic field of the planet, causing a geomagnetic storm, also known as a solar storm.
'Holes' in the corona of the sun are where solar winds emerge. In the Sun's atmosphere, these are cooler, less dense areas of plasma with more open magnetic fields. It is in such open regions that the solar winds can escape more easily, blowing electromagnetic radiation into space at high speeds; if the hole is facing Earth, the wind can blow directly towards our planet.
In the event of charged particles from the Sun hitting Earth's atmosphere, they are channelled down along Earth's magnetic field lines to the poles, where they interact with molecules in the upper atmosphere. Auroras are caused by the ionization of molecules, which makes them glow.
According to Space Weather's aurora forecast, 14 and 15 March have maximum levels of Kp 6 and Kp 5 respectively on the ten-point Kp index of geomagnetic activity. This means a strong possibility of bright, dynamic aurorae with the likelihood of auroral coronae, so it's a good time to go chasing lights in the sky.
If it seems like the Sun is a bit more active lately, that's because it is. Our star goes through 11-year activity cycles, with a marked peak and trough, known as solar maximum and solar minimum. Solar minimum, when the Sun's magnetic field is at its weakest, takes place when the Sun's magnetic poles switch places. The most recent solar minimum took place in December 2019.
That means we're currently escalating toward solar maximum when the solar magnetic field is at its strongest. Because the Sun's magnetic field controls its activity, this means that we'll be seeing an uptick in sunspots, solar flares and CMEs. (Sunspots are temporary regions of strong magnetic fields that form when the solar magnetic field tangles.)
Solar maximum is due to take place around July 2025. It can be difficult to predict how active any given cycle is going to be, but there's evidence to suggest we might be entering the strongest cycle recorded to date.
More powerful solar storms can cause more significant problems, so hopefully, our star will keep it relatively low key.