Earth Receives Over 5,000 Tonnes Of Extraterrestrial Dust Each Year

Every year, our planet is bombarded with dust from comets and asteroids. These interplanetary dust particles pass through our atmosphere, causing shooting stars to form.

The few micrometeorites that survive atmospheric entry can fall anywhere on Earth. Unless you're in Antarctica, it's nearly impossible to tell them apart from regular, terrestrial dust and soil. These interplanetary dust particles from comets or asteroids collide with our home planet.

Scientists have determined that over 5,000 tonnes of extraterrestrial dust fall to Earth each year.

An international program conducted by scientists from the CNRS, Université Paris-Saclay, and the National Museum of Natural History, with support from the French Polar Institute, determined that 5,200 tons of these micrometeorites reach the ground each year.

Six expeditions led by CNRS researcher Jean Duprat have taken place over the last two decades near the Franco-Italian Concordia station (Dome C), located about 1,100 kilometers off the coast of Adélie Land in the heart of Antarctica, which is virtually terrestrial dust-free. As a result, researchers know that any dust found in the snow has a high probability of being of extraterrestrial origin.

These expeditions gathered countless micrometeorite samples ranging in size from 30 to 200 micrometers. 

The researchers first calculated the annual flux of mass accreted on the surface per square meter per year based on these samples. According to the study published in the journal Earth & Planetary Science Letters, micrometeorites' annual flux for the entire planet is 5,200 tons per year.

According to the researchers, this is the primary source of extraterrestrial matter on our planet, far exceeding the flux of larger objects such as meteorites, which is less than ten tonnes per year.

The researchers also conducted a statistical analysis, which revealed that comets account for 80% of meteorites and asteroids for the remaining 20%. Comets are composed of ice, dust, rocky material, and organic compounds, whereas asteroids are composed of metals and rocky material.

In the future, scientists may be able to use this data to understand better interplanetary dust particles' role in the supply of water and carbonaceous molecules on the young Earth.