Australasian Science: Australia's authority on science since 1938

Asteroid To Skim Past Earth

By David Reneke

A newly discovered asteroid will pass menacingly close to Earth on 16 February 2013, but no one has to head for the hills or take shelter in a cave. The space rock, dubbed 2012 DA14, will pass 27,000km above Earth's surface, closer than some high orbiting communications satellites. For comparison, the distance between Earth and the moon is about 380,000 kilometres.

Through a telescope it will appear about the size of a distant star as it moves rapidly across the sky, almost eight times as fast a rifle bullet, at an altitude well below the orbit of most communications satellites!

NASA says this is the one of the largest asteroids ever to come this close to Earth, but other, much larger space rocks have crashed into Earth's surface millions of years ago, causing calamitous damage. The last asteroid to cause serious destruction on the ground exploded over a Siberian forest in 1908.

NASA and other dedicated astronomers routinely track asteroids and comets as part of a near Earth observation program designed to seek out potentially hazardous objects that could pose an impact risk to Earth.

Objects this size come close to Earth roughly every 30 years or so. For a brief time it should be bright enough that anyone with a small telescope or binoculars to spot it. The chance of a collision with one of our communication satellites is small, but not impossible.

Asteroid 2012 DA14 is thought to be about 50 metres across with an estimated mass of about 130,000 metric tons. If a space rock this size were to strike our planet it wouldn’t be Earth destroying but it would produce the equivalent of 2.4 megatons of TNT and form a crater about a kilometre wide.

To try and spot the asteroid from Australia, look a little below the Southern Cross from 4.30am onwards for its closest approach rendezvous at 6:26 am AEDT. You are looking for a slow moving ‘starlike’ object as it zips by the Earth from the South to West. Here in Australia, the morning twilight develops as the asteroid speeds by so get up early to watch the approach OK.”

For more information visit David’s webpage www.davidreneke.com