Passing asteroid holds key to origins of Earth

The 1,300ft-wide space rock, 2005 YU55, is the size of an aircraft carrier and whizzed past Earth at 11:28pm last night.

The last time a space rock this large came as close to Earth was in 1976, and such an event will not happen again until 2028.

Although the asteroid was too faint to see without a telescope, scientists were studying it closely to learn about its orbit and composition.

Its trajectory was also tracked by radar using ground-based antennae in California and Puerto Rico. Asteroids such as 2005 YU55 can provide clues about the formation of the Solar System, including the Earth.

Jay Tate, director of the Spaceguard Centre, an independent observatory and research facility near Knighton, Powys, said: “We will want to tell what the surface composition of the asteroid is. By learning what it is made of, we can question a great deal of what we know about how the planet is formed.”

The 2005 YU55 asteroid missed the Earth by 201,700 miles – a small distance in astronomical terms, although experts insisted there was no danger of the object hitting the planet.

If it were to veer off course, the impact could wipe out a city the size of London or New York, while landing in the sea would cause a 70ft-high tsunami.

Nasa has set up its Near Earth Object Programme, known as “Spaceguard”, to co-ordinate efforts to identify and trackpotentially hazardous space objects.

By the end of the decade, it aims to locate at least 90 per cent of an estimated 1,000 asteroids and comets larger than 1km (0.6 miles) in diameter.

Objects of this size are big enough to cause the mass extinction of most life on Earth. The asteroid believed to have wiped out the dinosaurs 65 million years ago measured 4.3 miles across. Mr Tate said spotting potential threats was vitally important: “There is a clear and present danger that we might be hit.”