Why are the Northern Lights so intense lately and how long will they last?

Most flares (class A, class B, and class C) are barely distinguishable from other solar activity occurring around them. But the most powerful — M class And X class flares – visible as bright bursts of light in orbiting telescopes such as NASA’s Solar Dynamics Observatory. They can also pose a risk to astronauts in orbiting spacecraft and tend to saturate the ionosphere on the dayside of Earth, disrupting long-range radio transmissions and satellite GPS signals.

The massive “prominent” shown at left exploded from the Sun on August 31, 2012, forming the CME shown at right as it moved away from the Sun. (NASA SDO, NASA/NOAA SOHO)

A. coronal mass ejection It typically occurs during a solar flare, when new connections made between magnetic fields around a sunspot result in part of one of the magnetic loops being severed and thrown away. The resulting explosion is sometimes called solar stormIt becomes a huge cloud of charged solar particles, energized and accelerated by the explosion, and carries a ‘piece’ of the Sun’s magnetic field with it as it expands into space.

If a CME passes near Earth, it has the potential to cause geomagnetic storms and auroras. However, its effect depends on the conditions inside the cloud.

What causes the brightest, most widespread aurorae?

Auroras are caused by the plunge of solar particles, usually electrons, into the Earth’s upper atmosphere. There they hit oxygen and nitrogen in the air, transferring their energy in the process. Oxygen and nitrogen then release this energy as flashes of colored light; oxygen produces green and red light (the two most common colors), and nitrogen generally emits blue and violet light. Different colors of light can mix with other hues such as yellow, orange and pink.

As mentioned above, a coronal mass ejection is a cloud of solar particles that explodes from the Sun, usually following a solar flare. The cloud has a certain density (the amount of particles it holds), the particles in it have a certain temperature (the energy they absorb from the Sun and solar flares), and the cloud moves at a certain speed. Considering that the cloud consists of moving charged particles, it carries electric and magnetic fields with it.

This diagram shows the interaction between a CME’s magnetic field and the Earth’s geomagnetic field; where a CME with a positive field direction is repelled (top example) and a CME with a negative field direction is attracted (bottom example). (Javalab/Scott Sutherland)

LEARN MORE: How do the Northern Lights shine? Here’s the science behind auroras

Under normal conditions, particles collected from the solar wind follow the outermost ‘layer’ of the Earth’s magnetic field into the atmosphere. Therefore, they flow only near the poles, and the auroras that form are confined to the same regions.