A different kind of storm

After a winter that brought seemingly endless blizzards, we'd be forgiven for feeling glum at news of yet another squall. Sunday, however, brought a different kind of storm to the northern portion of the United States – a much more beautiful one.

In this area, columns of light pulsed and danced as the day dwindled towards midnight, moving upwards towards a vast swirl overhead. The colors may have been less vivid than for skywatchers further north, but the aurora borealis was very much visible to the naked eye.

The display was caused by a severe geomagnetic storm. These occur when solar material hits the Earth after a coronal mass ejection.

The sun is currently nearing the peak of its process of switching its magnetic poles – a natural cycle that takes 11 years to complete. According to NASA, the sun is made of plasma: a gas-like matter in which electrons and ions have separated into a super-hot mix of charged particles, which create a magnetic field as they move.

The peak of the cycle is expected to occur in 2025. At this midway point, a "field reversal" will cause the sun's polar magnetic fields to deplete and then re-emerge with the opposite polarity.

As the sun builds towards this "solar maximum", its activity becomes more intense. Sunspots, solar flares and eruptions increase in frequency.

On Friday, a coronal mass ejection took place: a sudden and violent expulsion of billions of tons of plasma and magnetic material from the sun. This material streams outwards, impacting any planet in its path.

This particular coronal mass ejection erupted towards Earth and took until Sunday night to travel here.

Its arrival caused the geomagnetic storm that in turn sparked the aurora into life. Such storms occur when the energized particles from the sun hit the magnetosphere at estimated speeds of up to 45 million mph.

According to NASA, the magnetosphere is created by our own magnetic field and protects us from most of the particles emitted by the sun. When the particles hit, the magnetic field is peeled open, allowing the energetic solar wind particles to stream down the field lines and hit the atmosphere over the poles.

In other words, the Earth's magnetic field funneled those particles towards the North and South Poles. Doing so supercharged the molecules and triggered the aurora borealis (or Northern Lights).

The auroras borealis and australis are caused by collisions between gaseous particles in the atmosphere and charged particles from the sun's atmosphere. The color variations are caused by the type of gas particles that are colliding.

Missed the vivid aurora activity this year? Keep your eyes on the skies over the next year as the solar maximum approaches, as it's likely that even more spectacular sights are in store.