The dancing lights of the aurora bear silent witness to the awesome power of the Sun. Each curtain of brilliance that sweeps across the polar sky can be traced to a titanic explosion near the solar surface, 93 million miles away.
Each solar flare explosion releases a billion times the energy of an atomic bomb and usually rips away a giant swathe of the Sun’s atmosphere. This cloud of smashed atomshurtles through space, seething with electrical and magnetic forces.
Most disappear harmlessly into deep space but a small fraction head towards us. If one does strike the Earth, the particles are deflected into the polar regions by our planet’s natural shield of magnetism. Here they are funnelled inwards and strike our atmosphere. In doing so, they cause the atoms we breathe to glow, turning the sky into a giant fluorescent light tube.
The European sub arctic is the perfect place to connect with the aurorae and the history of their investigation. Swedish astronomers Olof Hiorter and Anders Celsius studied the lights during the mid-18th century, discovering thatthe aurorae make compasses behave erratically.
Norwegian scientist Kristian Birkeland extended their work during his 1902-1903 expedition. His observations allowed him to propose the correct theory for the electrical currents found in the polar lights, which led to our modern understanding of the phenomenon.
The Northern Lights are a true wonder of the Universe, and a reminder that our planet is intimately connected to a much wider cosmos.
Dr Stuart Clark is an astronomer, author and novelist. His latestbook is The Day Without Yesterday (Polygon Books, 2013). His website is www.stuartclark.com. You can see the Northern Lights for yourself with Transun.