Did you know hundreds of space rocks fall on your rooftops?

Every day, our planet sweeps up tons of space dust, a cosmic collection of tiny fragments shed by comets and asteroids as they journey through the solar system. These minuscule particles, known as micrometeoroids, are often no bigger than a grain of sand, yet they enter Earth's atmosphere at incredible speeds.

Surprisingly, most micrometeoroids survive their fiery descent. Instead of completely burning up, they slow down, cool off, and gently drift to the ground, settling on fields, oceans, and even the roofs of our homes.

Scientists estimate that approximately 5,200 tonnes (5.2 million kilograms) of extraterrestrial material reach Earth's surface annually. That's equivalent to the weight of over 800 elephants distributed across the globe each year.

A significant portion, around 80%, originates from comets. This cometary dust carries ancient ice, traces of water, and organic compounds, potentially playing a role in seeding life on Earth billions of years ago.

Why Micrometeoroids Survive the Journey

While larger space rocks can create spectacular fireballs and sometimes crash to Earth as meteorites, micrometeoroids behave differently.

Particles ranging from 30 to 400 micrometres in size experience intense heating, often melting into shiny, glassy spheres called cosmic spherules.

Friction in the upper atmosphere rapidly decelerates these particles, preventing them from completely vaporizing. They then fall silently, like a fine cosmic snow.

Research expeditions to Antarctica, where pristine snow helps preserve these extraterrestrial visitors, have precisely measured the annual influx. These studies confirm the constant arrival of micrometeoroids and highlight the dominance of cometary dust, providing valuable insights into the formation of our solar system.