NASA scientists are celebrating after seeing the first deliberate collision between a manmade projectile and a comet in outer space. Deep Impact, as the experiment is called, is intended to excavate material that has remained deep frozen since the solar system was formed four and a half billion years ago. This report from Roland Pease:

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Jubilation at NASA's Jet Propulsion Labs in California, as the first picture of the collision comes in from the Deep Impact mother ship. Just before six o clock GMT, the impactor, weighing a third of a ton, smashed into Comet Tempel 1 at a speed of thirty seven thousand kilometres an hour.

Telescopes across the world, and in Earth orbit, will be watching the giant spray of debris thrown out by the impact. The brightened comet in the constellation Virgo may even be visible to the naked eye, allowing members of the public around the world to join in this historic moment in astronomy.

The next twenty four hours could change our understanding of how the solar system formed, as pristine material from inside the comet is revealed for the first time in four and a half billion years.

Roland Pease, BBC

Listen to the words

Jubilation
joyful celebration

Propulsion
pushing forward

collision
impact

mother ship
the ship carrying the projectile

impactor
projectile, probe

the giant spray of debris
the massive flow of scattered fragments

constellation
a number of stars seen from the Earth as a group and often having a name

to the naked eye
without any instrument to help you see

to join in
to share

pristine
untouched, unspoilt

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