In 2024 skies over the Arctic region lit up with a dazzling display of colorful lights that was witnessed by people in several parts of USA, Europe and the Scandinavian countries. Known as Northern Lights or the Aurora Borealis this spectacle happens when the energized particles from the Sun hit Earth’s atmosphere and are funnelled towards the poles by the magnetic field that surrounds our planet. As the particles are redirected toward the poles, they interact with atoms of oxygen and nitrogen in our atmosphere, by depositing energy and causing the atmosphere to fluoresce. Earth’s invisible magnetic field in the upper atmosphere is created by the movement of molten iron within its outer core creating electric currents to generate magnetic field. This magnetic field is our protection from the harmful solar and cosmic radiations. The Aurora lights arepredominantly observed at higher latitudes as natural colourful light display in green, red, violet, purple, blue shades. In the southern hemisphere it occurs over Antarctica and are called as Aurora Australis.
Auroras are most commonly visible at latitudes higher than 55 degrees but during intense solar unrest it may be seen up to 30-degree latitude parallel. Our Sun is a huge ball of electrically charged hot gas that generate a powerful magnetic field when the gas moves. This magnetic field flips every 11 years and is called a Solar Cycle observed fromsunspot activity. In 2024, a spectacular display of auroras was observed over Leh in Ladakh and captured at India’s highest observatory at Hanle. This means that we are in the midst of an intense solar unrest period. According to World Data Center for the Sunspot Index and Long-term Solar Observation (SILSO), we are currently experiencing the maximum period of Solar Cycle 25; the last cycle was observed in April 2014.
Though, watching auroras could be an exhilarating experience in terms of its beauty, it reflects the most dangerous space hazard. Intense solar unrest periods send powerful bursts of energy and material into space during solar flares and coronal mass ejections. This can severely affect satellite electronics and limit their lifetime. Radiations from these solar flares can be dangerous for astronauts working on the International Space Stations. It becomes very important to improve our ability to predict the strength and duration of such intense solar flares. India’s Aditya- L1 mission launched in 2023 is one such attempt to study the Sun’s upper atmosphere and the effect of solar dynamics on space weather. NASA’s Parker Solar Probe is leading the solar studies in the space, today. Satellites could be put into safe mode and astronauts can delay their spacewalks, if solar unrest are predicted in advance.
I will end this essay on a personal note that Sun keeps on bombarding us with energetic particles, so if you wish to watch Northern Lights then the best place would be the town of Husavik in North Iceland, an 80 km drive from Akureyri where I witnessed the colourful dance of lights 16 years ago.
