What if you found a meteorite?

Sometimes a rock from space falls all the way to the ground. It is called a meteorite.

What if you found one? What would it look like? What should you do?

On a clear night you might see a shooting star: a bright streak as a bit of space rock burns up in the air. Most burn up completely, but a few pieces survive and land. Those are meteorites.

What if you found one? In this thought experiment, you can follow three paths: how to recognize a meteorite, what is inside one, and how museums and scientists study them. The first rule is simple: if you find a strange rock, do not touch it. Tell a grown-up.

NASA distinguishes three stages: a meteoroid is a rock in space, a meteor is the streak of light as it enters the atmosphere, and a meteorite is whatever survives to reach the ground. USGS notes that meteorites are very rare, yet many people find unusual rocks or pieces of metal and wonder whether they have found one.

This thought experiment imagines a possible find. It asks which features suggest a meteorite, what a real one could tell scientists, and how identification works. USGS stresses that rocks must be examined in person by experts; a description or photo is not enough. The safe first step for anyone is to leave the object and tell an adult.

Space rocks zoom into Earth's air very fast. Most of them burn up and make a shooting star.

A few pieces land. Most are small, from the size of a pebble to the size of a fist.

Every day, NASA estimates, about 48.5 tons of space material falls on Earth, mostly as dust and tiny grains. Rocks smaller than a football field usually break apart in the air, and less than 5 percent of the original rock usually makes it to the ground.

The meteorites that land are usually between the size of a pebble and a fist. They are easiest to spot in sandy deserts and on the ice of Antarctica, where dark rocks stand out.

Scientists estimate that about 48.5 tons (44,000 kg) of meteoritic material reaches Earth each day. Most objects smaller than a football field disintegrate as atmospheric pressure exceeds their strength, producing a bright flare; typically less than 5 percent of the original mass reaches the ground. Do not expect finds after meteor showers: their comet-derived material is fragile.

Meteorites are usually pebble- to fist-sized. They are most easily recovered from sandy deserts and Antarctica's ice fields. The US Antarctic Meteorite program, a partnership of NASA, the National Science Foundation, ANSMET and the Smithsonian, had recovered about 22,000 samples by 2016.

Let's pretend you see a strange, dark rock.

Do not touch it! It might be sharp. Tell a grown-up. A grown-up can ask a museum to help find out what it is.

Imagine you are walking and spot a dark, heavy-looking rock that seems different from all the others. Could it be from space? The first step is to leave it where it is and tell a grown-up, because unknown objects can be sharp or dangerous.

A grown-up can take photos, note exactly where it was found and contact a natural science museum, a university geology department or the state geological survey. Only experts who examine it in person can say for sure. If it were real, it might teach scientists about the early solar system.

Suppose a candidate turns up. The responsible sequence is clear: do not handle an unknown object, especially one that could be hot, sharp or industrial; let an adult record the location and photograph it; then contact experts. USGS lists a state geological survey, a natural science museum, or a college or university geology department, and notes that USGS itself does not verify meteorites.

Earth rocks and metallic slag can resemble meteorites, which is why identification needs examination in person. If the find were genuine, its value would be scientific: its composition and age might add a sample of an asteroid, the Moon or Mars to the record. That outcome is an idea; the steps are established practice.

Meteorites are often very heavy for their size. Many have iron inside.

Some have a dark, shiny skin that melted as they fell. They never have bubbles.

USGS lists clues. Meteorites are usually heavy for their size, because they contain metal and dense minerals. Most contain iron, so a magnet often sticks. Many have a thin, dark 'fusion crust' that melted as they fell through the air, and iron ones can have dents like thumbprints.

There are also clues that a rock is not a meteorite: bubbles, light-colored quartz crystals, or a black or red streak when it is scratched on unglazed tile. Even so, only experts can be sure.

USGS, adapting a University of New Mexico Meteorite Museum guide, lists positive signs: high density from metallic iron and dense minerals; magnetism, which may show only as a hanging magnet's attraction for stony types; irregular shapes with thumbprint-like pits called regmaglypts; and a thin fusion crust from melting in the atmosphere.

It also lists negative signs. Meteorites lack light-colored quartz, which is common in Earth's crust but unknown on other solar system bodies; they lack the bubbles typical of volcanic rock and slag; and they should leave no streak, since black or red streaks indicate magnetite or hematite. NASA adds that most stony falls go unrecognized, so iron meteorites dominate finds made long after the fall.

Many meteorites are older than any rock on Earth.

A few came from the Moon or from Mars! Museums keep them safe so scientists can study them.

Earth's rocks keep getting recycled by moving plates, so very old ones are rare. The oldest rocks found so far, in Canada, are about 4 billion years old, and some may be a little older. Many meteorites are older: measurements show they formed 4.53 to 4.58 billion years ago, as the solar system was forming.

Tens of thousands of meteorites have been found, and more are added every year: in 2025, scientists approved 1,944 new ones. Almost all come from asteroids, but a small share came from the Moon or Mars, blasted off by impacts. Scientists can tell Martian ones because they hold trapped gas that matches Mars's air.

USGS explains that plate tectonics has destroyed Earth's earliest crust; its 2007 page names the 4.03-billion-year-old Acasta Gneisses as the oldest rocks found, with zircon grains to about 4.4 billion years. A 2025 study in Science dated intrusions in Quebec's Nuvvuagittuq Greenstone Belt to at least 4.16 billion years, a claim some geochemists still treat with caution. More than 70 meteorites dated radiometrically formed between 4.53 and 4.58 billion years ago, and lead isotopes from the Canyon Diablo iron meteorite help fix Earth's age at 4.54 billion years.

Nearly all meteorites come from asteroids. The Moon and Mars supply a small share that grows as desert searches continue: of the 1,944 meteorites the Meteoritical Society approved in 2025, 86 were lunar and 24 Martian. Martian meteorites are identified by trapped gas matching Mars's atmosphere, and NASA's Dawn mission linked the HED meteorites to asteroid Vesta.