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Summer Science Exhibition 2011

Aurora explorer









The Royal Society, London, 6-9 Carlton House Terrace, London, SW1Y 5AG


Cluster's mission to the magnetosphere

The aurora seen from Tromso, Norway, 14 Feb 2007. The green colour comes from electrons colliding with atomic oxygen at a height of 100km above the Earth’s surface. Image Courtesy Pete Lawrence,


Have you ever wondered what the aurora are or how they work? Do you want to know about the Earth's invisible shield in space that protects us and our technology from solar radiation and explosions on the Sun? Are you interested in how to measure something in space that you can't even see?

'Cluster’ are four European Space Agency spacecraft that are exploring near Earth space and the magnetosphere, the invisible shield that surrounds us. At this exhibit you can learn about how the magnetosphere protects Earth from solar activity and about how it acts as the battery that powers the aurora.

How does it work?

Magnetic fields are everywhere in space. The Earth has one that stretches past the Moon and the Sun has one that reaches the edge of the solar system. The Sun's magnetic field is carried by the solar wind, a continuous but variable flow of electrically charged gas that streams away from the Sun at 1,000,000 miles per hour. The Earth's magnetic field makes a bubble in this flow of solar wind called the magnetosphere. It stops the solar wind hitting the Earth and blasting our atmosphere off into space.

The magnetosphere isn’t a perfect shield. It can let in some energy and particles from the solar wind and store them, but only up to a point. Once a large enough amount of energy is stored in the magnetosphere, it is explosively released, accelerating particles along the magnetic field towards the Earth. These particles collide with the gas molecules in the atmosphere, causing them to give off light – the aurora.

These pdf documents demonstrate some of the science of this exhibit.

See all exhibits from 2011