Recent Earth-passing asteroid 'civilization-killing monster in disguise

Washington, June 23 (ANI): A potentially hazardous asteroid thought to have been 500 meters wide, which drifted safely by coming within 14 lunar distances from Earth on Thursday, was a civilization-killing asteroid in disguise.

2012 LZ1 may not have been a danger, but much of the concern was rooted in the late warning of its detection - the asteroid was spotted only four days before closest approach.

One of the reasons for its late discovery is because it was detected in Southern Hemisphere skies, part of the world were we have few asteroid-watching programs. If it had been on a collision course with Earth, a few days notice is no time at all.

So, in the aftermath of the flyby, astronomers at the famous Arecibo Observatory in Puerto Rico used radar to image the interplanetary interloper.

What they uncovered was a surprise - Asteroid 2012 LZ1 is actually bigger than thought, in fact, it is quite a lot bigger. 2012 LZ1 is one kilometer wide, double the initial estimate.

The Arecibo team has determined that 2012 LZ1's surface is really dark, reflecting only 2-4 percent of the light that hits it, which contributed to the underestimated initial optical observations.

Arecibo used a powerful radar system, called the Arecibo Planetary Radar, to generate radio waves that were beamed in the asteroid's direction.

Incredible high-resolution images of surface features were attained by measuring the signals that bounced back to the radio antennae. Highly accurate measurements of the asteroid's physical size could be made.

"This object turned out to be quite a bit bigger than we expected, which shows how important radar observations can be, because we're still learning a lot about the population of asteroids," Discovery News quoted Arecibo Observatory's Ellen Howell as saying in a statement.

The follow-up observations have also helped astronomers make precision measurements of the asteroid's trajectory and other orbital characteristics.

With the help of Arecibo, astronomers have deduced that Earth will be safe from being hit by 2012 LZ1 for at least 750 years.

"The sensitivity of our radar has permitted us to measure this asteroid's properties and determine that it will not impact the Earth at least in the next 750 years," Mike Nolan, Director of Planetary Radar Sciences at Arecibo Observatory, said. (ANI)