Recent evidence has blurred the line between comets and asteroids, although until now neither ice nor organic material had been detected on the surface of an asteroid. Here, the spectroscopic detection of water ice and organic material on the asteroid 24 Themis is reported. Water ice thus seems to be more common on asteroids than previously thought, and may be widespread in asteroidal interiors at smaller heliocentric distances than expected

Recent evidence has blurred the line between comets and asteroids, although until now neither ice nor organic material had been detected on the surface of an asteroid. Here, the spectroscopic detection of water ice and organic material on the asteroid 24 Themis is reported. Water ice thus seems to be more common on asteroids than previously thought, and may be widespread in asteroidal interiors at smaller heliocentric distances than expected