Aurora - Dr Melanie Windridge – Wednesday 18th July 2018

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Melanie Windridge has explored the science and mythology of the Northern Lights and this month she shared many of the stories of her quest to explore her fascination in and our understanding of the Earth’s Aurora. Melanie is a physicist, specializing in fusion research. She is also an adventurous traveler, particularly at home in the world’s coldest places.

She shared the experience of her visits to many places where the aurora is visible – Lapland, Iceland, Canada, northern Scotland, and Spitzbergen – and of meeting people for whom the Northern Lights plays a significant part of their lives. She travelled, for example, with Sami herdsmen in northern Norway and learned of Sami mythology and the gradual dwindling of their nomadic way of life.

Dr Windridge interweaved these stories with explanations of the science of the Northern Lights. Aurora occur when electrons and protons, which are charged particles and form the greater part of the solar wind, interact with Earth’s magnetic field and elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of between 300 and 750 kilometers per second. They reach the Earth some 30 to 40 hours after leaving the sun. As the electrons enter the earth's upper atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the earth's surface. The colours generated relate to the energy levels available in atoms that are struck. Nitrogen producesthe blue and purple and oxygen produces green and red.

The auroras generally occur in ovals which centre on the magnetic poles and roughly correspond with the Arctic and Antarctic circles. There are times, though, when the lights are farther south, usually when sunspot activity is high. Sunspot activity follows an 11-year cycle. The next peak will occur in 2022.

Melanie highlighted the dangers that space weather poses for satellites in orbit, and for the power grid on the Earth’s surface. She outlined her own efforts to view the aurora, illustrating with her best attempts to capture an image how difficult it is to photograph the aurora’s rapidly-changing structure.