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Hello, comments and asteroids used to be regarded as the vermin of the solar system

Irritating rubble that got in the way of astronomers trying to study more interesting phenomena

It was difficult or even impossible for an observer of asteroids to book time using the world's best telescopes because they were regarded as

Unspectacular objects that could tell us little about the origins of the universe. However, this has changed

It's now thought that asteroids are the unused building blocks of planets

pristine material that has remained chemically unchanged since the creation of the solar system a snapshot of

Matter at the beginning of time at the present moment the Japanese probe

Hayabusa is a hundred and eighty million miles away

Pin to the back of the asteroid Itokawa attempting to gain our first samples of the chemical composition of an asteroid

Why did asteroids fail to form planets?

How do they differ from their celestial cousins the comets and are either unlikely to create another impact on planet Earth?

With me to discuss asteroids are Monica Grady professor of planetary and space sciences at the open university

Carolyn Crawford Rosses-Hard research fellow at the University of Cambridge and John Zanecki professor of space science at the open university

Monica Grady asteroids were discovered in the 18th century when they were looking for something else

Can you tell us about how the asteroid belt was discovered?

Yes, Boads law was

Well, it was a Titus boat and also by Kepler

understood or was studying the the gravitational

morphology or shape of the solar system and from Newton's laws they

Thought that there should be a planet from the way that things went around the Sun

...