Our sun has a cycle of activity, and as it grows more active, more northern (and southern) lights will be seen. That is what is happening right now as we enter Solar Cycle 25.
We have seen some stunning auroral displays, natural light displays in the sky, in more spots around the northern hemisphere in 2022 than usual. This winter, northern lights have been seen in northern England, for example, which is a sign of growing solar activity.
So why are we seeing more northern lights this year?
Solar flares erupt from the sun's surface and burst outwards as coronal mass ejections, which convey energy in the form of charged particles and magnetic fields. When a coronal mass ejection collides with Earth, it interacts with the magnetic field of the planet, causing a geomagnetic storm.
The Earth's magnetic field is essentially dipolar, with a tail stretched out by the solar wind and poles close to the geographic north and south poles, and it is at these high latitudes that charged particles can travel to reach Earth's atmosphere more easily.
The aurora borealis, often known as the northern lights, is caused by charged particles striking the upper atmosphere (ionosphere) and causing it to glow. These aren't just pretty pictures. Extreme space weather can disrupt a variety of systems, including power grids, aircraft, satellites, and radio communications.
These effects can cause unintended currents to flow across any electrical power infrastructure, resulting in damage and, in the worst-case scenario, power outages. The ionosphere is also disrupted, which has an impact on communications, and further out in space, where the charged particle environment becomes more energetic, satellites can be damaged.
The sun goes through a cycle of activity. Solar flares and coronal mass ejections are common during active years, but they are rare during quiet years. The solar cycles last around 11 years on average, but their duration and amount of activity vary. Sunspots - black patches on the sun's surface that correlate with the likelihood of solar flares - can be used to track the degree of solar activity.
The last several years have been characterized by low activity, and a solar minimum - a decrease in the number of sunspots - was recorded at the end of 2019.
The number of sunspots visible each day is progressively increasing, indicating that we are currently in the rising phase of the new solar cycle of activity. We're also seeing an increase in the number of solar flares.
Solar flares are divided into three types based on their X-ray emissions: X-class flares are the most powerful; they can cause continental-scale radio blackouts and city-wide power outages. Medium-sized flares, known as M-class flares, can create brief radio blackouts in Earth's polar regions. C-class flares are tiny and have limited visible effects on Earth.
It's difficult to forecast how busy the next phase of the new solar cycle will be because each solar cycle is unique in terms of duration and activity level. For now, if you are in the northern part of the world, enjoy these rare, magnificent sky ribbons while you can.
