Meteorite facts that really are true

Objects orbiting the Sun can meet Earth at between about 11 and 72 km/s. Meteorites that survive usually came in at the slower end, under about 25 km/s.

Once the air has slowed it to a few kilometres per second, usually 20 to 30 km up, the glow stops and the stone falls unseen for several minutes. Wind during dark flight can carry it kilometres sideways.

Moving ice carries meteorites to places where it is blocked and worn away by wind, leaving dark stones on blue ice. Expeditions have recovered more than 45,000 there.

In dry deserts, meteorites weather slowly and dark stones stand out on pale ground. Most meteorites sold today come from the Sahara and Arabian deserts.

Stony meteorites are typically 3.0 to 3.7 g/cm³ and irons about 7.5 to 8, against 2.6 to 2.8 for most Earth rocks. A meteorite feels heavy for its size.

The great majority of suspected meteorites sent to museums turn out to be slag, iron ore, basalt or concretions. Experts call them meteor-wrongs.

After a bright fireball, falling stones can show up on weather radar. Hunters have used radar images to find several recent falls in the United States and elsewhere.

Recordings from many cameras let scientists work out a fireball's path and where pieces fell. The 2021 Winchcombe meteorite in England was found this way, using the UK Fireball Alliance's camera networks.

The criss-cross pattern grows only when iron-nickel metal cools by a few degrees per million years, inside an asteroid core. Nothing on Earth's surface cools that slowly, though forgers sometimes etch fake patterns on steel.

Several minerals, such as schreibersite-rich phosphides, the calcium sulphide oldhamite and many tiny rarities first described from meteorites, are unknown or extremely rare in Earth rocks.

Ureilites contain tiny diamonds, and some chondrites hold nanodiamonds older than the Sun. They are far too small to see without a microscope.

Carbonaceous chondrites can hold up to about 20% water, locked inside clay minerals. Such rocks may have helped deliver water to the early Earth.

Carbonaceous chondrites like Murchison contain dozens of amino acids, sugars and the nucleobases found in DNA and RNA, all made without life. Samples from asteroid Bennu contain them too.

Presolar grains, tiny crystals of diamond, silicon carbide and graphite, formed around other stars before the Solar System existed. Some in Murchison are up to about 7 billion years old.

The olive-green crystals in pallasites are olivine, the same mineral as the gemstone peridot. Gem-quality peridot cut from pallasites is among the rarest gemstones.

The oldest meteorite material, about 4,567 million years old, beats Earth's oldest minerals (zircons about 4.4 billion years old) and oldest rocks (about 4 billion years).

Most contain iron-nickel metal, which rusts in damp air. Some irons also contain lawrencite, a chloride that keeps them rusting even indoors.

Nearly all meteorites are fragments of asteroids, broken off in collisions in the asteroid belt and nudged into Earth-crossing orbits by Jupiter's gravity.

Large impacts on the Moon and Mars throw rocks fast enough to escape, and some reach Earth. Several hundred lunar and several hundred Martian meteorites are known.

HED meteorites come from asteroid 4 Vesta, LL chondrites match asteroid Itokawa sampled by Hayabusa, and the Almahata Sitta stones came from asteroid 2008 TC3, tracked before it hit Earth.

Tiny pockets of gas trapped in glass inside some Martian meteorites match the Martian atmosphere measured by the Viking landers. That is how their origin was proved in 1983.

Cosmic rays leave a measurable record. Most stony meteorites spent between a few million and a hundred million years in space after breaking off their parent asteroid; irons often hundreds of millions.

Sample-return missions to Itokawa, Ryugu and Bennu found material matching known meteorite types, confirming the link.

Estimates vary widely, but tens of tonnes of extraterrestrial material, almost all fine dust, arrive every day.

Howardites, eucrites and diogenites come from the crust and mantle of asteroid 4 Vesta. NASA's Dawn spacecraft confirmed the match when it orbited Vesta in 2011 and 2012.

Besides Ann Hodges in 1954, a boy in Mbale, Uganda, was hit by a small fragment in 1992 without harm, and a few other minor strikes are reported. Being hit remains extraordinarily unlikely.

Peekskill smashed a car in New York in 1992, Claxton flattened a mailbox in Georgia in 1984, and in 1965 a Barwell stone came through a window in Leicestershire. Stones occasionally punch through roofs too.

In the 18th century most scholars dismissed such reports as superstition. Ernst Chladni's 1794 book and the fall of thousands of stones at L'Aigle, France, in 1803 changed their minds.

Iron beads from Gerzeh in Egypt, about 5,200 years old, are made of meteoritic iron, long before people could smelt iron from ore.

A 2016 analysis showed that the iron blade found with his mummy has the nickel and cobalt content of an iron meteorite.

For centuries the Inuit of north-west Greenland chipped iron from the Cape York meteorite masses to make blades and harpoon tips.

Several ancient cults centred on stones said to have fallen from the sky, such as the black stone of Elagabal brought from Emesa to Rome. The Sinagua people of Arizona buried the Winona meteorite like a person.

Before 1800 many scholars thought fallen stones were thrown out by distant volcanoes, formed by lightning, or condensed in the air.

In 1802 the British chemist Edward Charles Howard found nickel in both stony and iron meteorites, showing they share a chemistry unlike Earth rocks. Howardites are named after him.

Meteorites are named after the nearest town or geographic feature. Desert and Antarctic finds get the area's name plus a number, such as Northwest Africa 7034 or Allan Hills 84001.

Scientists accept a meteorite only once it has been classified and its name approved by the Meteoritical Society's Nomenclature Committee and published in the Meteoritical Bulletin.

Fame adds value: pieces of Chelyabinsk, the car-hitting Peekskill stone and the Sylacauga stone that struck Ann Hodges all sold for far more than ordinary chondrites.