In 2021, two people headed into Canterbury Cathedral. They, like so many before them, were in search of a message from the heavens. Remarkably, they actually found it.

The duo were planetary scientists at the University of Kent and what they found on the roof of the iconic building may come as something of a surprise.

They were searching for micrometeorites – tiny particles of meteorites and even comets – which had fallen, as dust, onto the Cathedral.

What they discovered, some believe, could be the sparks of life on Earth itself. And what they contain could go someway towards unlocking the secrets of the solar system.

Perhaps more remarkably, the very cosmic particles they were hunting for are, more likely than not, under our very feet. In fact, there’s every chance they hit us while we’re outside.

“Up until recently,” explains Penny Wozniakiewicz in her pursuit of cosmic dust, “it was generally regarded that trying to search for micrometeorites anywhere other than places like the Antarctic – where we have a really low background level of terrestrial dust – would be very difficult.

“They are arriving on Earth in large numbers, so we estimate that around 20- to 40,000 tonnes of extraterrestrial dust is arriving every year. But that's spread over the whole surface of the planet. There have been estimates that it amounts to about one to six particles per metre square per year arriving if you spread it equally.

“But in places other than the Antarctic you've obviously got large amounts of terrestrial dust that we're making, and this can get very difficult to search through for cosmic dust.”

So let’s establish, first, just what cosmic dust is.

More often than not, meteorites revolve around the Sun between Mars and Jupiter. Many of them are thought to have been formed a mind-bending 4.6 billion years ago. Comet dust comes from the celestial bodies of ice and dust moving through the universe from as far away as Neptune.

But if they collide, then smaller chunks break off. Then the journey to Earth begins – which can take tens of thousands of years.

Fellow planetary scientist Matthias van Ginneken explains: “Micrometeorites are the particles that survive atmospheric entry. Most of it gets burnt up when reaching the atmosphere because of collisions with air molecules – they become what we call meteoric smoke.

“But micrometeorites are between like a few tens of microns in size up to, let's say, two millimetres. So the very big ones you can see with your naked eye, like you can see a black dot on your finger.”

The best place to find them is on the roofs of tall buildings, where the extraterrestrial dust settles with that we create on Earth. Which is where the university researchers come in – trying to find the out-of-space needles in a microscopic dusty haystack.

“If you're lucky, one hits you,” says Penny, “but not hard. We should say that. By the time they reach the surface, they are floating down.” And, of course, barely – if at all – visible.

After securing permission from the Cathedral and undergoing the strict safety procedures insisted upon, they climbed to the roof and started collecting the dust.

Matthias adds: “Then you take it back to the laboratory and wash the sample because roofs are pretty dirty. There's a lot of bird poo, for example. Then, once it's clean, you can use a microscope and then spend hours and hours just looking for spheres. And it's a very long process.”

Penny explains: "A really cool characteristic of a lot of extraterrestrial dust is that they contain magnetic material within them. So you can increase your chances of finding a micrometeorite by using a magnet to actually separate out the magnetic portion and then search through that.

“Then, if you look for the particles that have actually come through the atmosphere and melted, they'll form very distinctive spheres, very beautiful spheres. We do make spherical particles through our activities, but it's in much lower numbers compared.

“In short, you can indeed find cosmic particles amongst the dust on rooftops.”

So what, you may ask, does all this mean? Well, the objective of their work is to use the particles to try and identify the “asteroid family” from which they once formed part of. This then “gives you an idea of the inventory of matter in the solar system” and its evolution.

In fact, it is possible that it was this constant falling of cosmic dust which actually initiated life on the planet.

Matthaus says: “To make it very simple, let's say that we know amino acids are the building blocks of life basically. They’re rather simple organic molecules, so carbon-based molecules that are necessary for life to appear.

“These molecules were found on meteorites. And micrometeorites as well. So there is a possibility that the building blocks of life didn't appear on Earth but appeared in space, then were delivered to early Earth.

“And then the presence of water and energy allow these molecules to get more and more complex – eventually leading to the operation of life.”

Given the scale of this cosmic dust, it gives scientists a far greater opportunity to study rather than waiting for big chunks of meteorites to fall to Earth.

Yet, only a handful in this country are actively researching micrometeorites.

Now the pair from the university are hoping to encourage others to get involved. By using a 3D printer to create a far larger model of the micrometeorites they have discovered, they have gone into schools to reveal their findings.

In addition, they are hoping to set up a network of sites where they could collect samples – although they warn against anyone doing it without all the necessary safety requirements.

Penny adds: “Several cathedrals around the UK, through Canterbury Cathedral, have said they are interested in the project so we're hoping to go and sample from each of those rooftops as well, so that we can have a series of them.

“The idea is we hope to build this into a citizen science project.

“Ideally, we want to expand on it so it became nationwide even worldwide. Then you can start to compare the micrometeorites you find. And look for different types, but also compare them in different locations to see if there's some interesting patterns based on latitude for instance, or whether that tells you more.”

So next time you’re clearing your gutters, bear in mind that some of the dust may have spent billions of years to reach you.