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Home > Animals & Nature > Articles > Is it true that the aurora borealis produces sound as well as light

Is it true that the aurora borealis produces sound as well as light

01:00 Mon 08th Oct 2001 | Animals & Nature

A.� No, the aurora borealis, otherwise known as the Northern Lights, is a purely visual phenomenon. Suggestions that sounds accompany the ripples of lights are highly unlikely since the atmosphere is too thin where the lights occur to be able to carry sounds to the earth's surface and our ears.

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The likeliest explanation for such claims is that observer's brain mis-interprets electrical impulses coming from the eyes as sounds.

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Q.� What causes the northern lights

A.� The lights are the result of an interaction of our earth's magnetic field with the solar wind, which contains a mixture of charged particles blown away from the sun, which continuously flows around and bombards the earth's magnetic field.

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The charged particles are drawn down towards the earth's strong magnetic poles, regions known as auroral ovals, in the upper atmosphere. Here, they collide with gas in the atmosphere, causing the atoms to give off light.

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This is why the phenomenon is most likely to be seen the further north, or south, for the aurora australis, you are. However if the solar wind increases then the lights can be seen further a field, even in southern England.

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Q.� What is the solar wind

A.� It is created by the interaction of the sun's atmosphere, which is made of hydrogen, and its magnetic field. Particles from the atmosphere constantly boil off the sun and shoot outwards at very high speeds, creating solar wind.

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Q.� Why does the aurora borealis display different colours

A.� Gases present in our atmosphere glow different colours depending on their electrical state, whether they're charged or neutral, and on the energy of the particle hitting them.

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High altitude oxygen, around 200 miles up produces the rare all red auroras, while lower altitude oxygen, around 60 miles up, produces a yellow green glow. Charged nitrogen produces a blue light, whereas neutral nitrogen glows red.

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Q.� How high are the auroras

A.� The lowest point is at least 40 miles above the earth while the highest extends 600 miles.

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Q.� When is the best time to see them

A.� To see an aurora you need complete darkness and clear skies. In Britain the best times to look are the March and September equinoxes.\

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by Lisa Cardy

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