What does the inside of an asteroid look like?
Many asteroids are rubble piles, loose heaps of rocks and dust with gaps between, while others are solid rock or metal.
Nobody has cut an asteroid in half, but scientists have clever ways to work out what is inside.
One method is to measure how heavy an asteroid is for its size. Spacecraft can measure an asteroid's mass by watching how its gravity tugs on them. When scientists divide the mass by the size, they find that many asteroids are surprisingly light. That means they must have lots of empty space inside.
These asteroids are called rubble piles. Imagine a pile of rocks, gravel and dust, all clumped together by gravity, with gaps in between like a bag of marbles. Itokawa, Ryugu and Bennu, all visited by spacecraft, are rubble piles. When the OSIRIS-REx spacecraft touched Bennu in 2020, its arm sank into the surface easily, as if it were a ball pit.
Other asteroids may be more solid. Some large asteroids, such as Vesta, are thought to have layers like Earth: a metal core, a rocky middle and a crust on top. Some metal-rich asteroids, such as Psyche, may be partly made of iron.
Future missions, like Europe's Hera, will use radar to peek inside an asteroid called Dimorphos, a bit like an X-ray of a space rock.