What can we learn from a seashell?

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

In April this year, Harvard University physics student Amir Siraj made a discovery of international significance. Here is his personal take on what was achieved.

Imagine standing on a beach, watching shells drift ashore and back out to sea. You could simply glance at the shells and not give a second thought to the assumption that they reflect the local environment. 

Alternatively, you could carefully observe the shore, noticing, every once in a while, an exotic shell that had clearly travelled a long way to reach you. Out of curiosity, you could jot down the features of that shell, its direction of origin, and, when the tide has gone down, perhaps even pick up a small fragment that had permanently washed ashore.  

You would wonder where the exotic shell came from, which animal inhabited it, and what environment it thrived in, using your knowledge of the shell’s properties to infer answers to these questions. Just by spending some time at the local beach, you could come away with a deeper understanding of another part of the globe. 

Just like shells washing ashore, most meteoroids hitting the Earth are local in origin, sharing the same birthplace as our planet. But every so often, a meteoroid originating from a foreign planetary system strikes our atmosphere, providing us with a brief window of time to learn as much as we can about it and its distant home as it burns up. 

If we are lucky, a small fragment will fall down to the Earth in a place where we can retrieve it for further study. 

On the afternoon of Tuesday 2 April 2019, I, with the help of my mentor Professor Avi Loeb, discovered the first interstellar meteor larger than dust. The meteor had burned up in the atmosphere on 8 January 2014, off the coast of Manus Island, Papua New Guinea.

While we were able to ascertain its speed and approximate direction of origin, its properties remain unknown, with its only possible remnants resting on the seabed of the Pacific Ocean. 

Much like the discovery of an imprint of an exotic shell on a local beach would indicate that seashells reflect much more than the immediate environment, the discovery of the first interstellar meteor tells us that a wealth of knowledge about the distant cosmos is within our reach, as long as we are willing to seek it out.

 Up until now, astronomy has been conducted by studying signals from distant locales, with untold quantities of knowledge remaining elusive due to the prohibitive distances we would have to travel to obtain and study foreign physical samples. 

“The real voyage of discovery consists not in seeking new landscapes but in having new eyes,” the French novelist Marcel Proust once said. We urge the world to look through “new eyes,” ready to graciously accept interstellar visitors as gifts from nature and to use their properties to unlock secrets of the distant cosmos. 

In a recent paper, we outlined a worldwide network of all-sky cameras that would be suitable for the job, costing only a small fraction of the budget for LIGO, the gravitational wave detector. Such a network would open a new realm in astronomy, allowing us to better understand the composition, origins, and prospects for life in distant planetary systems.

While it’s easy to go to a local beach and take its landscape for granted, bringing “new eyes” and an open mind can allow for seemingly impossible discoveries about distant parts of the world. 

When we bring humility and curiosity to everything we look at, opening ourselves to any and all possibilities, it is then that we truly see nature, in all its beauty, interconnectedness, and complexity.

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