UK to join 'killer' asteroid hunt

UK astronomers are to join a search for Earth-threatening asteroids measuring less than 1km (0.6 miles) across.
Researchers from three universities have signed an agreement to use a one of the world's most advanced telescopes - the Pan-Starrs observatory in Hawaii.
Pan-Starrs, sited on the island of Maui, is equipped with a huge digital camera.
While searching for near-Earth asteroids, it will build up the most detailed image yet of the Universe.
This will enable astronomers to investigate small Solar System objects and search for exploding stars, to produce three-dimensional maps of galaxies and dark matter, to measure the properties of dark energy and to investigate how galaxies have evolved.
Researchers from the University of Durham, Queen's University Belfast and the University of Edinburgh have signed an agreement to start using the facility.
"The current generation of search telescopes are designed for the objects about 1km across and larger, because if one of those hits, it could cause instant global climate change," said Alan Fitzsimmons, a professor of astronomy at Queen's University Belfast.
"The smaller objects need a larger telescope and a more efficient camera system - they're the kinds of objects Pan-Starrs has been designed to detect.
"Even though they're smaller and don't cause as much damage, there are more of them and they hit more frequently."
Eye on the sky
Although sub-1km asteroids might not cause devastation on a global scale, they could cause death and destruction at a local and regional level, potentially wiping out millions of lives.
The last significant event like this occurred in 1908, when an asteroid or comet exploded above the Tunguska region of Siberia. The area was sparsely populated and, as a result, did not cause extensive loss of life.

The biggest asteroids are easy to spot; the smaller ones less soBut a similar explosion over an urbanised area could have more dramatic consequences.
Dr Fitzsimmons and his colleagues at Queen's will head up UK efforts to identify potentially deadly asteroids.
Researchers at Durham and Edinburgh will primarily work on imaging more distant objects in the Universe as well as studying the evolution of galaxies.
John Peacock, professor of cosmology at Edinburgh University, commented: "Pan-Starrs will be an amazing tool for studying the make-up of the Universe.
"It will let us measure the properties of dark matter and dark energy in many different ways, more precisely than ever before."
The planned Pan-Starrs telescope will use four 1.8m telescopes. A prototype telescope called "PS1" has been built on the Haleakala volcanic peak in Hawaii.