Music in Space

Professor William Daughton

Space Plasma

 

Most people think of the space between the planets and the sun as an empty vacuum devoid of matter. In reality, the solar system is filled with an ionized gas known as a plasma. Most of this plasma originates from the sun where an outward flow is generated called the solar wind, shown at left. The solar wind from the sun interacts with the Earth's magnetic field and produces the magnetosphere, a type of bubble in space with plasma from both solar and terrestrial origin.

Plasma is a very hot gas in which the electrons have been stripped from atoms, because of the high temperature, to form a gas of electrons and poitively charged ions. In a fully thermalized equilibrium state, these electrons and the positive ions will oscillate about their equilibrium positions. However, any perturbation to this equilibrium would displace the charged particles and set up electric and magnetic fields.

 

An example of the effects of such huge perturbations in the Sun, known as solar storms, cause many subsequent effects which can be observed from Earth. Aurora Borealis or the Northern Lights are such an example.

 

Rich variety of of plasma waves are possible in some of these plasmas. Some of these waves have a close analogy with sound waves from our everyday experience while others are quite different.While it is not possible to hear these waves directly with the human ear, the waves can be measured with a variety of other techniques and the waveforms can then be converted to ordinary sound. Professor Daughton will discuss all this and give examples of how these waves from space actually sound.

 

An example of a space craft riding a plasma wave.