Asteroid's passage no threat to Earth

An asteroid predicted to swing close by Earth tomorrow morning does not pose any threat, Dunedin Astronomical Society president Peter Jaquiery says. The asteroid, about half the size of a rugby field, will whizz past about 27,700km above Earth about 8.24am New Zealand time in what Nasa is calling a one-in-40-year event.

Mr Jaquiery said the asteroid would not be visible in Dunedin skies, because it was passing during daylight hours. It would however, be visible through a telescope in eastern Europe, Australia and Asia.

The passing by of the asteroid - named 2012 DA 14 - was no cause for worry as Nasa knew ''very precisely'' were it was going and ''there was absolutely no way it was going to hit Earth''. Asteroids did not change course over a short period of time, he said.

While the asteroid, at 45m in diameter, was not ''terribly big'', if one of similar size hit Earth ''you really wouldn't want to be under it''.

The last time an asteroid of similar size hit was in 1908, in the Siberian wilderness. It caused a significant explosion and wiped out 2000sq km of forest.

Mr Jaquiery said if an asteroid was on a collision course for Earth there was little that current technology could do about it.

Nasa estimated an asteroid of similar size to 2012 DA 14 passed close to Earth every 40 years, on average, but hit Earth only once every 1200 years.

The asteroid would pass inside the orbit of communications satellites, but Nasa expected it to pass through an area free of satellites.

- vaughan.elder@odt.co.nz