Where do meteorites come from?

Parent bodies

Many assignments remain relationships to a family rather than identification of one asteroid. Especially well supported are links between HED meteorites and Vesta, and between lunar or Martian meteorites and their respective worlds.

From the asteroid belt to an Earth-crossing orbit

Collisions in the asteroid belt release fragments from parent bodies. Small objects also change orbit through uneven thermal radiation from their surfaces, known as the Yarkovsky effect, and can slowly drift into orbital resonances.

Resonances, especially with Jupiter, can strongly alter these orbits and deliver material to near-Earth space. The journey may take millions of years; cosmic-ray exposure ages help estimate the time since ejection from the parent body.

How origin is determined

Researchers compare mineralogy, elemental chemistry, oxygen isotopes, trapped gases, ages and spectra. No single measurement is always sufficient; an origin becomes convincing when several independent lines of evidence agree.

HED meteorites are linked to asteroid Vesta. Lunar meteorites match lunar rocks, while Martian meteorites match the Martian atmosphere among other evidence. For many chondrites, only an asteroid family or chemically related but unobserved parent body can be proposed.