Space clouds

Last updated 11:09 23/03/2010

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Alex Taylor, of Mokoia Intermediate School, asks:

I heard of an eruption on the Sun which sent out millions of magnetic particles. What will be their effect on the Earth and satellites?

Brian Fraser, a space physicist at the University of Newcastle in Australia, responds:

This is an example of the turbulent "weather" that can be experienced in space.

On April 7, 1997 a large solar flare or magnetic cloud erupted on the Sun and was observed by telescopes on the Solar and Heliospheric Observatory spacecraft located between the Sun and Earth.

It was predicted by Nasa and other scientists that this cloud may, but not necessarily would, envelope the Earth three or four days later. This prediction of a possible encounter with Earth was not fulfilled.

The cloud passed Earth and its effects on the planet were not severe. In this instance the world-wide media had "beat-up" the story beyond its scientific content.

However, earlier in the year on January 9, 1997, a similar magnetic cloud erupted on the Sun and collided with Earth, producing northern and southern lights (the aurora) at high latitudes, and affected radio and TV transmissions. More seriously, it also destroyed the US$200 million Telstar 401 communications satellite.

A magnetic cloud outburst from the Sun is the spasmodic release of thermo-nuclear fusion energy in the form of high-speed plasma streams. The plasma is a hot gas consisting of protons and electrons with a temperature of more than a million degrees Celsius.

Travelling at 500-1000 kilometres per second, these clouds take three to four days to reach Earth, where they interact with the region of space influenced by the Earth's magnetic field, the magnetosphere, to produce magnetic storms and dump electrons and protons into the well-known Van Allan radiation belts.

It is the increased energy and density of these atomic particles that upsets satellites, radio communications, and the Global Positioning Satellite (GPS) navigation system.

Send questions to Ask-A-Scientist, PO Box 31-035, Christchurch 8444, or email questions@ask-a-scientist.net

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