Explainers: step by step
12 of the big processes behind meteorites, each told in five to eight steps with a diagram for every step. Start with how the Solar System formed, or jump to whichever question you have.
How the Solar System formed
From a cold cloud of gas and dust to the Sun, the planets and the leftover rubble that falls to Earth as meteorites.
Origins · 7 stepsHow chondrules formed
Tiny frozen droplets fill most stony meteorites. What melted them is one of the oldest puzzles in meteoritics; here are the clues and the leading ideas.
Asteroids · 7 stepsHow an asteroid differentiates
How some early asteroids melted and separated into a metal core, a rocky mantle and a basalt crust, and how meteorites sample every layer.
Iron meteorites · 7 stepsHow Widmanstätten patterns grow
Why an etched iron meteorite shows a criss-cross lattice of metal bands, and how it records millions of years of slow cooling inside an asteroid's core.
Dating · 7 stepsRadiometric dating and isochrons
How radioactive atoms act as clocks, why an isochron gets round the problem of the starting amount, and how meteorites gave the age of the Solar System.
Classification · 7 stepsHow meteorites are classified
From stone, iron or stony-iron down to a code like L6 S4 W2: the questions scientists ask, in order, to place a new meteorite in its group.
Falls and fireballs · 7 stepsAtmospheric entry: from orbit to dark flight
What happens to a space rock in the last minutes of its journey, from a speed of tens of kilometres per second to a cool stone on the ground.
Falls and fireballs · 7 stepsHow fireball cameras triangulate a fall
How networks of sky cameras turn a few seconds of light into a path through the air, an orbit around the Sun and a search area on the ground.
Meteor showers · 7 stepsHow a meteor shower forms
From a comet's dusty tail to a stream of grit around the Sun that Earth meets on the same nights every year, and why showers seem to come from one point in the sky.
Impacts · 7 stepsHow an impact crater forms
Contact, excavation and collapse: how a fast-moving asteroid blasts out a bowl, and why big craters end up with central peaks and rings.
Mars · 7 stepsHow a rock leaves Mars and reaches Earth
From an asteroid impact on Mars to a stone in the desert: how Martian meteorites make the journey, and how we know where they came from.
Planetary defence · 7 stepsHow DART changed an asteroid's orbit
In 2022 a spacecraft deliberately crashed into a small asteroid moon and shortened its orbit by about half an hour. Here is how the test was designed, done and measured.
The 4.6-billion-year timeline
From the first solids to today: zoom from the whole history of the Solar System down to the space age, with links to the impacts, people and missions along the way.