This track features the ‘sound’ of whistler mode waves in the solar wind. These waves are electromagnetic plasma waves that are also observed ubiquitously in planetary magnetospheres. Near to the Sun they are observed to have large amplitudes and cover a narrow range of frequencies. They are observed in regions where the magnetic field is more variable and are often associated with small increases in the speed of solar wind. The whistler mode waves we hear in this piece were detected by the Fields Experiment on the Parker Solar Probe.

The duet between the whistler mode waves and the theremin is beguiling. It is hard to hear when one starts and the other continues because the sounds of the whistler mode waves are almost impossible to imagine. They have density and two insistent characters, one is almost like a mosquito of huge proportions, the other sounds very similar to the ‘Tardis’ sounds of the BBC Radiophonic Lab.

In our presentations on the 'Sounds' of Space one of the most common questions we have received is why certain early electronic instruments sound similar to these space ‘sounds’. While we cannot answer such a question we can state that the instrument many people ask about is the theremin, an instrument originally commissioned by the Soviet government wishing to advance its work into proximity sensors. Invented by Lev Sergeyevich Termen (Leon Theremin), it was popularised by the virtuoso Clara Rockmore between the wars, being capable of playing standard classical repertoire for instruments such as the violin, without the player even touching the instrument. With the rise of mainstream electronic music after the Second World War the theremin found its place in a number of science fiction scores such as 'The Day the Earth Stood Still' and in songs such as 'Good Vibrations'. In this track we hear a Moog based on the original design with two sensors, one for frequency (pitch) and the other for amplitude (volume). This track takes advantage of the theremin’s ability to move across large glissandi (slurred intervals) as well as its ‘analogue’; character, which is capable of creating both piercing and round sounds in close proximity.

The artwork by Scarborough places an imagined sun against a background of neural networks. Using flow and colour to evoke the contemplative, she pays homage to to the work of the abstract 'colour field' painter Mark Rothko. The title 'Sunethesia' is our word play on the word Synesthesia. Given this is when you hear music, but you see shapes or you hear a word or a name and instantly see a colour it seemed a perfect title choice.