Sooner or later, scientists who study Earth-crossing asteroids say, astronomers will find one that has a significant chance of striking the planet.

He studied comets and asteroids.

Scientists will take this opportunity to study asteroids along the Rosetta path.

The instrument has been used to study our galaxy, asteroids and comets.

Soviet scientists talk openly of their plans for missions to Mars and to study comets and asteroids.

He also studied asteroids (he discovered 76 Freia) and nebulae.

It is also one of the best studied potentially hazardous asteroids.

The main reason to study asteroids, he says, is the clues they hold to the origins of the solar system.

Next he studied asteroids and variable stars, meanwhile hoping for an academic appointment.

He studied asteroids and discovered several himself.