2024: The Year of the Northern Lights

Experiencing the aurora borealis has always been on the bucket list for many people, whether they be scientific-minded, or simply romantics. Luckily for all the sky-lovers, 2024 appears to be the year of the Northern Lights, but what exactly is the aurora borealis and how does it happen?

The Northern Lights, or the aurora borealis, is a phenomenon involving spectacular ribbons of green, red, and even purple light that ripple across the sky. Their beauty has continued to captivate scientists and skywatchers alike for as long as one can fathom. But regardless of all its splendour, it is a rather violent event.

The dancing of lights that we observe in the night sky is caused by the unstable activities of the Sun. The Sun is an enormous ball of super-hot ionised gas. The ejection of extremely powerful charged particles from the Sun’s corona, the outermost part of its atmosphere, is a natural process called solar wind. When these strong solar winds slam into the Earth’s ionosphere (upper atmosphere), the aurora is born.

“These particles are deflected towards the poles of Earth by our planet’s magnetic field and interact with our atmosphere, depositing energy and causing the atmosphere to fluoresce,” says Billy Teets, the director of Dyer Observatory at Vanderbilt University in Nashville, Tennessee (1). As for the different colours, the chemical composition of the Earth’s atmosphere plays a vital role. Teets continued, “Some of the dominant colours seen in aurorae are red, a hue produced by the nitrogen molecules, and green, which is produced by oxygen molecules.” (1)

The Northern Lights are often observed in Alaska, Iceland, Scandinavia, and Canada. However, during periods of intense geomagnetic activities, due to the broadening of auroral zones, people in lower altitudes, like the UK, have a better chance at seeing the aurora too! Similar to the lights in the North Pole, it is indeed termed southern lights in the South Pole, which is observed in countries like Australia and New Zealand. Surprisingly enough, Earth isn’t the only planet that undergoes this phenomenon — planets like Jupiter and Saturn do too!

But why have we observed so many shows of Northern Lights at lower altitudes this year? To answer this question, we return to the concept of the unstable activities of the Sun, especially its coronal region. Unstable solar activity has reached its peak this year after a long interval of roughly eleven years.

Coronal holes are temporary features that can form on the upper atmosphere of the Sun — vast areas from which solar winds stream out due to openings in the Sun’s magnetic field. Along with the coronal holes on the sun’s atmosphere, ‘sunspots’ also develop on the sun’s surface or the photosphere. These spots, which can be viewed in the visible light wavelength, can produce explosive events like solar flares. These solar flares refer to the aforementioned fast-moving charged particles and can take roughly one to three days to reach Earth. The Sun goes through a long eleven-year activity cycle, which can be measured by counting the number of sunspots. Sunspots are at their peak during solar maximum, which leads to an increased frequency of solar storms.

These solar cycles have been recorded since the eighteenth century. In 2020, a panel of scientists predicted that this solar cycle — solar cycle 25 — would be fairly weak, but later in 2023 this view was revised and a stronger peak of activity with solar maximum expected between January and October 2024, was forecasted. (2)

The likelihood of observing the Northern Lights in the UK depends on several factors including how far north a person is, how disturbed the earth’s magnetic field is, and the weather conditions — since a clear sky is a necessity for spotting the aurora. (2) Regardless of all these requirements, we have observed some spectacular shows of colourful lights throughout the second half of 2023 and will continue to do so for roughly another year, before the current solar maximum stars recede for yet another decade.

Words by Archita Nath

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