Space 'weather' close-up

The unseen clouds of gas that envelope the Earth

By BBC News Online science editor Dr David Whitehouse

A satellite in orbit high above the Earth is providing a unique insight into the mysteries of "space weather".

Rivers of sub-atomic particles form rings in the Earth's upper atmosphere

Image, launched on 25 March, 2000, into an elliptical orbit, traverses the Earth's magnetic outer sheath, the magnetosphere, taking pictures and measurements.

It was the first satellite dedicated to imaging this region, which is controlled by the Earth's magnetic field and contains super hot ionised gas in the form of a plasma.

Its images are showing how energy in plasma billowing from the Sun gets inside the Earth's magnetic cocoon and causes aurorae and geomagnetic storms.

Clouds and rivers

Image is moving through clouds and rivers of plasma taking pictures of a mysterious region that is largely invisible.

The aurora of 15 July, 2000

The detailed movements of ions and electrons responsible for the "weather" above the Earth's upper atmosphere were almost completely unknown.

In the journal Science, researchers produced the first comprehensive global images of the plasma regions of the inner magnetosphere.

From them, scientists can study, in a way never possible before, the large-scale dynamics of the magnetosphere and the interactions of its plasma populations.

Phones and electricity

Obtaining images of this important region has been technically very difficult.

The spacecraft's sensors use novel technologies that allow them to see the thin clouds of plasma and their motions.

As well as studying plasma in a natural laboratory with conditions that could not be reproduced on Earth, the observations may have practical benefits.

Events in the magnetosphere can disturb communication systems from cell phones to satellites, as well as disrupting electrical distribution grids.