At 11 metres in diameter, asteroid 2012 BX34 that passed by the Earth on Friday was tiny compared with the 400-metre-wide asteroid 2005 YU55, shown here, which swung by the Earth on Nov. 8. (NASA/JPL-Caltech )
An asteroid about 11 metres in diameter roared past the Earth early Friday in one of the closest approaches ever recorded for such an event, astronomers say.
Detected Wednesday, the asteroid, named 2012 BX34, passed within 60,000 kilometres of Earth, less than one-fifth of the distance to the moon. It was not visible to the naked eye.
“It makes it in to the top 20 closest approaches, but it’s sufficiently far away … that there’s absolutely no chance of it hitting us,” Gareth Williams, associate director of the US-based Minor Planet Center, told the BBC.
The previous closest asteroid to pass by the Earth, named 2011 MD, was in June 2011.
Hundreds of asteroids swarm around the sun and routinely cross the orbit of the Earth, generally without cause for concern because they rarely hit.
2005 YU55, a 400-metre-wide asteroid about the size of an aircraft carrier, swung by the Earth at a distance of 325,072 kilometres on Nov. 8.
The last major asteroid to hit the Earth, which was about 10 kilometres in diameter, struck the Yucatan 65 million years ago, wiping out the dinosaurs, according to Bob McDonald, of CBC’s Quirks & Quarks.
“There is good evidence that the Earth had been smacked equally hard many more times before that, each time changing the character of life on the planet, McDonald said. “In fact, you could say that asteroids have had as much influence on the evolution of life on Earth as natural selection.”