How many kilos of meteorites fall to Earth in a year (and where are they most likely to be found)

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Geoff Evatt / University of Manchester

Have you ever wondered how much of the rocky material that meteorites make hits our planet each year?

This is a recurring question among scientists, and now they have come to a new conclusion.

A team of scientists from the UK provided a new estimate of the amount of space rock that falls to Earth each year.

And the account that the specialists took out is that it only exceeds … 16,000 kilos.

To give an idea, it would be approximately what a large waste truck weighs.

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That calculation includes only meteorite material above 50 grams of mass. It does not take into account the dust that is continually settling on the planet.

But, according to specialists, that estimate gives a good idea of ​​the overall amount of rock debris raining down from space.

Dwhere do they fall the most meteorites

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University of Manchester / Katie Joy

“The vast majority of objects that hit Earth are really small”Dr. Geoff Evatt explained.

“We are talking about objects for which, when they hit the ground, the fragments add up to more than 50 grams. So, typically, they range from 50 grams to 10 kilos in total. Objects larger than this are very, very rare,” the mathematician from the University of Manchester told the BBC.

In addition, the study, produced together with colleagues from the University of Cambridge, Imperial College London and the British Antarctic Survey, allows for a risk assessment for the entire planet.

This means that scientists They also measured where more meteorites fall on Earth.

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And the number of falls at the poles it is approximately 60% of what it is calculated that it falls in Ecuador.

This explains why it would be more convenient to place any long-term contingency facility at higher latitudes.

An example of that is the World Seed Bank, whose objective is to store copies of the Earth’s plants in case of crisis. It is located 78 degrees north in the Svalbard archipelago in Norway.

Meteor hunting

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The Crop Trust

The new estimate, published in the magazine Geology, emerged from the project to undertake the first hunt british meteorite in the Antarctic.

The researchers involved wanted to make sure they would visit the most productive areas to conduct such a search.

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The Antarctic continent is the place on Earth where most of the meteorites have recovered, and this occurs for good reason: the contrast “black on white” of space rocks falling in the snow And the ice makes searching much easier.

And hunters often go to places where the movement of the ice sheet concentrates the meteorological material, called stranding areas.

Evatt and his colleagues calculated how many objects should be in the chosen area, a place called the Outer Recovery Ice Fields, near the Shackleton mountain range in East Antarctica.

And they practically met their expectations, finding about 120 meteorites in two systematic searches during 2019 and 2020.

Image copyright
Geoff Evatt

But after having produced a reliable flow for the number of falls on the chosen terrain, the scientists realized that they could use this knowledge to carry out a global assessment.

Built-in orbital mechanics – how Earth’s gravity will attract nearby material – to determine how rates can vary by latitude, generated a model of approximately 17,000 falls a year.

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And this can be proved by looking at the data of the fireball events. Orbiting satellites that track lightning in storms also catch the trail of fire from a space rock sinking into the atmosphere.

“Satellites monitor these explosions in the sky, calculating the energy of the events and also the longitude and latitude of the place where they occur,” said Evatt.

“And from this you can see how they vary around the world with latitude, and the curve you get from these fireballs matches what we independently model using an applied mathematical approach,” he added.

Fireball events reported by US government sensors (April 1988 to March 2020)

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A.B.Chamberlin (JPL-Caltech)

For Professor Sara Russell, who leads the planetary materials group at the London Museum of Natural History but was not involved in the research, “this is an amazing study, and this estimate seems to be correct. “

“We believe that a total of approximately 40,000 tons (or 40,000,000 kilograms) of extraterrestrial material falls to Earth each year, but the vast majority is in the form of small grains of dust.”

“This is a very difficult measurement to make accurately and only half a dozen meteorites are seen falling each year. Of course, almost all meteor falls are not observed because they fall into the sea, unpopulated areas, or just” One he’s watching! “he described to the BBC.

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