Light is more than just what we see. The light spectrum can provide information about astrophysical objects — and in different wavelengths, it can provide different types of information. We can observe the sky through X-rays, visible light, gamma rays — all of which are waves at different frequencies. For sounds, something similar happens: it exists in many frequencies. High pitched sounds have higher frequencies than low ones, which is why electric guitars sound higher than bass guitars, their frequencies are a lot higher.
So what would happen if you would turn light (or other types of astronomic data) into sounds? This is technically called sonification — the use of non-speech data to represent sounds. You basically take some type of data and translate it into pitch, volume, and other parameters that define sounds.
It’s not as silly or unheard of as it sounds. Scientists convert things into sounds for a number of reasons. For instance, take the Geiger counter, an electronic instrument used to measure ionizing radiation. If the radiation is high enough, you hear an increase of repetitions in the click sound from the instrument. The same can be done with astronomical data, with many lines of code, scientists can translate astronomical data into sounds. So, without further ado, here are some of the coolest sounds in the universe.
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The Pillars of Creation
In the sonification in the Eagle Nebula, you can hear a combination of both optical and X-ray bands. The pitches change according to the position of the light frequencies observed, the result reminds us of a sci-fi movie soundtrack. As we listen to the features from the left to the right, the dusty parts form the Pillars as a whir, it’s eerily apparent that we’re hearing something cosmic.
Using Solar and Heliospheric Observatory (SOHO)’s data, we can listen to our star’s plasma flowing and forming eruptions. The sound is pretty peaceful for a 5,778 K environment.
In one of Parker Solar Probe’s flybys, the spacecraft collect data from Venus’ upper atmosphere. The planet’s ionosphere emits radio waves naturally that were easily sonified.
The Bullet Cluster is famous for being proof dark matter is out there. In its sonification, the dark matter part (in blue) is lower, while the matter part (in pink) has a higher pitch. This is one of the most melodic cosmic sounds you’ll ever hear, though it does have a distinctively eerie tune as well.
This sonification is different from the others. We hear the sounds emanating from the centre of the Tycho’s supernova remnant and continue with the sounds of the stars visible in that plane. Inside the remnant, the sound is continuous, outside we hear distinct notes which are the stars nearby.
With a musical approach, the sci-art outreach project SYSTEM Sounds, not just sonify data, but also make sure the sounds are harmonic. It’s even better when nature provides naturally harmonical systems.
The most incredible sonification of all comes from the TRAPPIST-1 system, a relatively close system “just” 39.1 light-years away. Six of the planets orbiting the red dwarf are in an orbital resonance that means they pull each other in pairs and their rotation match in the integer ratios 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2. So the first two planets influence each other gravitationally — for every eight orbits completed by TRAPPIST-1a, TRAPPIST-1b completes five. If it all sounds a bit confusing, look at the video below and it will make more sense
SYSTEM Sounds got the advantage of the harmony in the TRAPPIST-1 system and sonified the planets orbiting their star. In the audio, first, you hear each planet completing one orbit as a piano note. Then to emphasise the orbit resonance, the team added a drum sound when the planets matched in orbit. The result is a super cool song.
This type of project shows a new perspective and a new way of looking at data. Much more than just taking photos and looking that them, this is a way to showcase the many nuances and differences often present in astronomic data. Furthermore, this work is excellent to include visually impaired people in astronomical observation, making the cosmos accessible for those who can’t see it. If you have a friend suffering from visual impairment who would like to know what space is like — here’s your chance to show them.
A collection of sonification is found in the Chandra X-ray Center’s ‘A Universe of Sound‘ and SYSTEM Sounds.