Soaring to the depths of our universe, gallant spacecraft roam the cosmos, snapping images of celestial wonders. Some spacecraft have instruments capable of capturing radio emissions. When scientists convert these to sound waves to audio, the results are eerie to hear. Although these sounds might appear to be intelligent signals from another civilization … they are just natural space phenomena. Click on each title to hear!
The background static sound you hear is the sound of the sky. It’s the same “white noise” you see and hear when you turn on an old television where there is no channel. White noise are radio photons from space that are trapped in the atmosphere. The high-pitched “UFO noise” is the sound of a “meteor” reflecting back sounds from an earth transmitter. Our planet is covered with many radio-transmitters that are giving off radio signals. As a meteor comes through our atmosphere, it heats up and charges the atoms around it leaving a trail of excited atoms behind it. The trail of excited atoms acts like a mirror and sends back radio emissions, which creates the high-pitch UFO noise you hear.
The bow shock is a discontinuity that forms in the solar wind when the supersonic solar wind encounters the magnetic field of a planet. This phenomena is very similar to the shock wave that forms upstream of an aircraft moving at a supersonic speed. The bow shock crossing is indicated by the “abrupt burst” of electric field noise, which is caused by electrical currents that flow in the shock.
Saturn has lightning deep in its atmosphere, which generates strong radio emissions similar to the cracks and pops you hear on an AM radio during a thunderstorm. First discovered by the Voyager 1 spacecraft, these radio emissions are the only direct evidence of lightning at Saturn, so far. Since the lightning-related radio emissions are emitted over a broad range of frequencies, a burst appears at whatever frequency the instrument happens to be tuned to at the moment of the burst. These recording from the Voyager spacecraft were converted to sound by using the amplitude and duration of the bursts to create an audio signal.
These sounds are known as “whistlers”, which are produced by lightning traveling along Earth’s magnetic field line from one hemisphere to the other. In the ionized gas that exists in this region of space, the high frequencies travel faster than the low frequencies, thereby dispersing the wave from the lightning stroke into a whistling tone that decreases in frequency with increasing time, hence the term “whistler.”
As the Cassini spacecraft approached Saturn it was able to listen in on a solar storm wreaking havoc on the planet’s magnetic field. As waves of particles from the Sun moved up and down Saturn’s magnetic field, the particles changed in velocity and produced these changing pitch radio frequencies. The higher pitched notes are higher energy/frequency photons and the lower pitches are lower energy/frequency photons.
Jovian electron cyclotron emissions are intense narrow-banded emissions, generated by energetic electrons spiraling along the magnetic field lines of Jupiter and its magnetized moons. The frequency bands of the electron cyclotron emissions occur at harmonics or very precise multiples of the electron cyclotron frequency, a characteristic frequency of the plasma surrounding the planet. The frequencies of the electron cyclotron emission bands track the variations in the electron cyclotron frequency, which varies with the strength of the magnetic field. The resulting tones are high-pitched monotones, which move up and down in the frequency.