Our gigantic universe is home to galaxies, planets, stars, asteroids and other astronomical bodies that we still don’t know about. All of these have lifecycles — from birth through middle age and finally death, which can provide material for the birth of other celestial bodies. While not exactly like the cycle of human lives on Earth, these cosmic cycles follow their own fascinating patterns. It is truly remarkable to note how everything works according to natural laws and cycles.

However, the mysteries of the cosmos are deep and vast. One of the enigmas associated with space is the silence and it is indeed overwhelming. Have you ever wondered if these astronomical bodies produced sounds? If yes, then you’re asking the right scientific question and the answer is: sound can’t travel without any medium like air or water. Since there is no medium for sound to travel, space is considered a vacuum devoid of atmosphere.

Without air or other mediums to carry sound waves, human ears cannot detect the typical noises we associate with sound; however, it doesn’t mean the universe is entirely silent — yes, the astronomical bodies spread throughout our vast universe are quite active regarding energy and waves that they produce!

If you study physics, you’ll probably know that electromagnetic phenomena such as stars, planets and black holes emit various forms of energy and types of waves like radio waves and X-rays. While we can’t hear these waves directly, just as we can’t hear radio waves from our radio stations, scientists, using advanced technology, convert these phenomena into sound waves through a process called sonification, giving us a unique auditory perspective of these celestial bodies. Amazing, isn’t it?

Let’s explore how these space phenomena are detected and converted into something we can hear.

The science behind converting signals into sound

The wonders of space aren’t limited to what we can see. Several of our spacecraft act like cosmic ears, equipped with special instruments to capture the electromagnetic ‘whispers’ of the universe. These electromagnetic waves typically fall within the radio and microwave frequency ranges, which are far outside the range of human hearing. The Voyager’s plasma wave detector, Cassini’s radio and plasma experiments, and Hubble’s spectrometers all pick up these invisible signals from space.

By using a technique called frequency translation, scientists convert these signals into sounds, which our human ears can understand — typically between 20 Hz and 20,000 Hz. This manipulation allows us to hear the electromagnetic emissions from stars, planets and galaxies.

It’s important to note that what we “hear” isn’t actual sound from space, but rather converted signals!

The types of sound in space

Electromagnetic waves exist in various forms and frequencies, ranging from radio waves to X-rays. Nasa’s space missions, such as Voyager and Cassini, have detected these waves, along with plasma oscillations and changes in magnetic fields around planets and their moons.

Plasma waves: Plasma is like a soup of charged particles, such as electrons and ions, which are extremely thin and widely dispersed. When these particles move, they push and pull on each other because of their electric charges. This movement creates patterns or waves in the plasma, similar to ripples in water when you throw in a stone.

Vibrations and oscillations: Many celestial bodies, including some stars and planets, shake or vibrate at certain frequencies. These vibrations can happen because of events inside them, like solar flares, sunspots or activity in a planet’s atmosphere. These vibrations are then turned into sound waves we can hear and study.

Famous examples of space sounds

Saturn’s Rings: The magnificent rings of Saturn are truly marvels in their own right. Nasa’s Cassini spacecraft captured the electromagnetic signals emitted by the charged particles in Saturn’s rings. After converting the signals into soundwaves, it revealed the dynamic and energetic interactions taking place within the rings. The resulting sound resembled a ‘whooshing’ noise, just like the wind gently sweeping through.

The Sun’s activity: In most videos or clips we see about the Sun, we witness the fiery activity occurring on its surface — indeed, it is a cauldron of constant energy, emitting solar flares and numerous other energetic particles. Don’t you imagine the sound to be much like the water boils and bubbles? However, contrary to this, the collected vibrations and oscillations’ data which, when converted, created a unique type of sound much like the howling winds of a storm or the deep rumblings of distant thunder, echoing through the vastness of space.

Pulsar sounds: Pulsars are neutron stars that rotate rapidly, emitting beams of radiation at regular intervals. Scientists, when converting these beams into sound, provided us with the rhythmic ‘heartbeat’ of the pulsar.

Black holes: One of the most mysterious and fascinating objects in the universe! Still being studied and will remain under the scrutiny of scientists and researchers. Black holes emit low-frequency gravitational waves that ripple through space-time. When scientists converted these waves, they produced eerie and haunting sounds — straight from a horror movie!

How does space sound interpretation help?

Our natural curiosity as humans pushes us to explore and uncover the mysteries of the universe. One incredible discovery in astronomy is that the vibrations and waves from celestial bodies can be turned into sound. These ‘space sounds’ aren’t just fascinating; they’re also incredibly useful.

By listening to these audio translations of cosmic waves, astronomers can uncover important details about stars and planets. They can learn about things like temperature, composition, movement and even what’s happening deep inside —like the structure and age of a star’s core. This approach is called asteroseismology, it is like unlocking the secrets of stars without ever needing to travel to them. Isn’t that amazing? Moreover, scientists can predict space weather, which impacts satellite communications, GPS systems and even power grids on Earth.

Impact on popular culture

Space sounds are often described as ‘space music,’ by popular culture and have inspired many works of art, science fiction and music. For example, many space-themed movies and documentaries feature real recordings of space sounds to evoke a sense of wonder. Films like 2001: A Space Odyssey and documentaries like The Universe use these converted space sounds to create a feeling of awe and immersion.

So far, we have come to understand that while the universe may be silent in the traditional sense, the celestial bodies within it are not. I am literally in awe of how scientists are capturing and translating these cosmic sounds — something we could hardly have imagined in our lifetimes. These sounds of the universe remind us that even in the vast silence of space, there exists a symphony of activity waiting to be discovered and understood.

(Also see Page 7 for more details about a website called Sounds of Space)

Published in Dawn, Young World, January 11th, 2025