Space Weather and the Aurora | Royal Meteorological Society

With January coming to an end, it will only be a few weeks until the vernal equinox. In 2013 it falls on 20 March.

Spring is the time of year when there is an increase in the number of aurora, both Borealis in the northern, and Australis in the southern hemisphere.

The Aurora, a kind of "space weather" are caused by energy coming up against the Earth's magnetic field. The energy comes from the sun, which acts as an enormous power plant, with temperatures reaching in excess of 14 million C in places. On the outer layers of the sun, the energy moves in huge eddies called convection cells. These currents create electrical fields in the sun. On the surface, plasma is formed, which can then travel outwards and break away from the sun in huge pieces, forming what are known as solar storms. The image below shows the Earth to scale, against solar activity. There are different kinds of activity, including solar storms, coronal mass ejections (CMEs) and sun spots.

A solar storm can reach speeds of over 8 million kilometers an hour. After 6 hours it can pass the planet Mercury and after 12 hours, Venus. After 18 hours the solar storm may reach Earth. When the storm reaches Earth, it comes up against our magnetic shield. This can interact with the solar energy and create a funnel, which sends the energy around the Earth and towards the poles, where it can sometimes be seen as beautiful green lights.

The sun is currently reaching the peak of its 11 year activity cycle, but it is thought that 2013 will be a year of relatively low activity.

Images and information courtesy of NASA
Below - Excellent video on the subject

RMetS article on Space Weather >>

For a discussion of solar flares and coronal mass ejections (CMEs) See the NASA site >>

Source: http://www.rmets.org/space-weather-and-aurora-0

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