“In the distant past, people were both amazed and terrified by comets, perceiving them as laden stars that appeared in the sky unannounced. Today, we know that they are giant bodies of ice, leftovers from the solar system’s formation 4.5 billion years ago. We have even visited eight of them, capturing incredible images some of which are close-ups revealing their bizarre icy surfaces or streaming tails. We have also listened to some of the eerie noises that surround them, allowing us to experience what a comet, an ancient object from the very edge of the solar system, sounds like.”
What is Comet
“A comet is a mixture of gases, rock, and dust that orbits the Sun. You can think of them as enormous dirty snowballs tumbling through space. There are likely billions of frozen comets orbiting far beyond Neptune in a region called the Kuiper Belt, or even in the more distant and mysterious region called the Oort Cloud, a hypothetical shell of icy objects that surrounds the entire solar system. When frozen, comets can be the size of a town, but occasionally a comet’s orbit brings it close to the Sun, heating it up and causing dust and gases to spew into space, creating an enormous glowing atmosphere sometimes larger than a planet. This magnificent celestial feature is called the coma.”
“It was within the coma that the first-ever sound recording of a comet was captured as NASA’s Stardust spacecraft flew through the gas and dust surrounding Comet 9P/Tempel in 2011. The incredible audio clip, recording 1 of 3, provides a brief example of what it sounds like to pass by a comet, as icy dust particles streaming off the ancient object pelted the spacecraft, resembling a hail of bullet-like particles. This sound recording highlighted the damaging environment that surrounds a comet. Interestingly, a few years before Stardust listened to 9P/Tempel, it also visited another comet named 81P/Wild.”
NASA Research Data
“In 2004, NASA’s Stardust spacecraft collected the first-ever sample from a comet’s coma and sent it back to Earth for study. This image gives you an idea of what the material surrounding a comet looks like. In 2005, NASA’s Deep Impact spacecraft released a lander designed to crash into Comet 9P/Tempel, and as this incredible footage reveals, the probe successfully smashed into the comet, causing a bright flash of ice and dust to burst into space. The probe even captured images as it approached the comet, showing us step by step until it eventually crashed into its surface.
But in 2014, we got to hear exactly what it sounds like to land on a comet when the Rosetta spacecraft released a soft-landing probe designed to touch down on the surface of Comet 67P.”
Cosmic Snowball
“This sound recording is only 2 seconds long, capturing the moment a cosmic snowball tumbled through space. While this short recording might not seem very significant, the thud you just heard is the very first time we’ve ever captured the sound of a human-made object making contact with a comet upon landing. But it wasn’t just that thud that allowed us to hear sounds from this comet; its mother spacecraft, Rosetta, also discovered a very strange sound—one that was described as resembling a song, as though Comet 67P was singing.
This next audio clip, recording 3 of 3, is thought to capture oscillations in the magnetic field around the comet, recorded when the spacecraft was about 100 km away. This is the bizarre sound of a ‘singing’ comet.”
The Comic Song
“The comet song would not be audible to the human ear because it is emitted at 40 to 50 mHz, far below the range of human hearing, which typically picks up sounds between 20 Hz and 20 kHz. To make the sound audible to humans, Rosetta scientists increased the frequencies by 10,000 times, allowing us to experience this strange comet song. Scientists believe the sounds are likely produced by the comet’s activity, perhaps as it releases neutral particles into space, which then become electrically charged or ionized. However, the precise physical mechanism behind these oscillations remains a mystery.”
Dr. Abid Hussain Nawaz, Post Doc and Ph.D.
Ajmal Rabbani, Physics Subject Educationist and Researcher
