Meteorites across the sciences

1Astronomy and the birth of the Solar System

Almost all meteorites are fragments of asteroids, with a small number from the Moon and Mars. That makes them real samples of the Solar System that scientists can study in a laboratory, rather than only through a telescope.

The oldest of them, the chondrites, hold tiny grains and droplets that formed in the disc of gas and dust around the young Sun, before the planets existed. Following a meteorite's path through space also connects it to orbital dynamics: the gravity of the Sun and Jupiter, and the slow drift of fragments from the asteroid belt towards Earth.

#Solar System formation#Micrometeorites#Asteroid geology#AsteroidsAsteroidsClose approaches#Vesta#Space missionsChondritesSpace missionsMission timelineComets#Comets

2Chemistry and cosmochemistry

Meteorites are chemical archives. Their minerals record the temperatures and pressures in which they formed, and the ratios of their isotopes act as fingerprints that link a meteorite to its parent body. Radioactive isotopes work as clocks: uranium–lead, rubidium–strontium, samarium–neodymium and other methods give ages accurate to within a few million years, or even less, for rocks billions of years old.

Some meteorites contain microscopic grains that formed around other stars before the Sun was born, a direct link to how stars make the elements. Carbon-rich meteorites carry amino acids, sugars and nucleobases made without life, which ties meteoritics to the chemistry of life's origins.

#Cosmochemistry#Dating and isotopes#Organic chemistry in space#Carbonaceous chondritesCAIsMurchisonMeteorite minerals

3Geology and the Earth sciences

Meteorites are classified much as geologists classify Earth rocks, by their minerals and structure: chondrites, achondrites, irons and stony-irons. Together they sample every layer of worlds that melted and separated into core, mantle and crust.

Impacts make meteorites part of Earth's own geology too. Craters, shatter cones, shocked quartz and high-pressure minerals such as coesite, stishovite and ringwoodite reveal ancient impacts, and rocks changed by impacts, called impactites, are studied around the world. Because plate tectonics and erosion have erased most of Earth's earliest rocks, meteorites and the Moon hold clues to our planet's early history that Earth itself has lost.

#Planetary differentiationFossil micrometeorites and the ancient air#Impact processes#Impact craters#Iron meteoritesVredefortImpact eventsShatter cones

4Physics: motion, energy and atmospheric entry

Every meteorite fall is physics in action. Newton's laws and gravity govern a meteoroid's orbit. When it meets the atmosphere at tens of kilometres per second, the air in front of it is compressed and heated, the surface melts away (ablation), and a glowing fireball and sometimes a sonic boom follow.

The energy involved can be enormous. A large meteoroid can explode high in the air, as one did over Chelyabinsk in 2013, while bigger bodies blast out craters. Measuring these energies is the basis of planetary defence: finding and tracking near-Earth asteroids, and testing ways to change their paths.

#The physics of meteors#Fireballs#Planetary defenceImpact calculatorImpact energy explainedChelyabinsk airburstChelyabinskAblationFusion crustHow micrometeorites survive entry

5Biology and astrobiology

Amino acids, sugars and nucleobases found in meteorites show that some of the building blocks of life form naturally in space. One long-standing idea is that falling meteorites and dust helped deliver such compounds to the young Earth.

Many meteorites also contain water-bearing minerals, evidence that warm water once flowed through rock inside young asteroids. That links meteoritics to astrobiology, the study of life's potential beyond Earth, and to the question of which worlds could ever have been habitable.

#AstrobiologyWater and organics from space dust#Organic chemistry in space#MarsALH 84001Allende

6History, culture and education

Meteorites have shaped human history. Falls were recorded as wonders and omens, meteoritic iron was worked into treasured objects long before people could smelt iron from ore, and events such as Ensisheim in 1492 and Tunguska in 1908 still fascinate people today. Meteorites have inspired art and writing, and reflection on our place in the cosmos.

Today they are curated in museums and research collections around the world, catalogued, shared with scientists and used to teach geology, astronomy, chemistry and physics in classrooms everywhere.

The science itself was built by people: physicists who were laughed at for saying stones fall from space, curators who gathered the great collections, hunters who walked deserts and ice sheets, and farmers and householders who saw a meteorite land.

Free coursesPeople of meteoriticsTimelineOn this dayFalls by year#History and culture#Famous falls#Collecting and the lawHistoryEnsisheimTunguskaMyths and folklore

7How it all connects

Meteorites sit where the sciences meet because each one is several things at once:

• Astronomical objects that become geological samples.
• Chemical archives that preserve the ingredients of life.
• Physical projectiles that shape planetary surfaces.
• Historical events that have influenced human culture.

Together they provide physical evidence of processes that stretch from the lives of ancient stars, to the formation of planets, to the origins of life itself.