It appears that Earth just escaped a likely 'doomsday scenario' as the US space agency National Aeronautics and Space Administration (NASA) reported that an asteroid missed the planet by a hairline on Monday.

The asteroid, which NASA said is almost the same size as a regular commercial bus, passed by Earth at 1700 GMT and kept a distance of at least 12,000 kilometres above the planet before its gravity forced the stray rock from entering out atmosphere.

However, NASA has clarified that despite its size, the asteroid named by scientists as 2011 MD would normally be harmless once it enters Earth's atmosphere as the rock will splinter and burn if its composition is largely made of stones.

The space agency admitted though that it will be a different story if the asteroid proved to be fortified by iron minerals, which can survive the fiery friction upon impact on the planet's atmosphere.

Still, NASA said that even that scenario is too remote as 2011 MD posed no risk of even entering Earth's orbital space.

The event, however, is a learning opportunity for scientists as NASA stressed on its report that "there is no chance that 2011 MD will hit Earth but scientists will use the close pass as opportunity to study it with radar observations."

The 'close encounter', according to NASA scientists brought the 2011 MD close enough above the coast of Antarctica and below Earth's satellite belt though the space agency noted that no risks of collisions with satellites have been considered by experts.

Even with the asteroid entering the so-called geosynchronous satellite area, NASA said that the rock will have to contend with an immense space populated by too little orbiting man-made machines.

Also, Space.com said that the rock was hardly a threat to the International Space Station that orbits 354 kilometres above the Earth.

NASA also noted that asteroids such as the size of 2011 MD are almost regular events every six years though not everyone was detected by observers.

Yet an experienced space watcher, using sufficiently powerful telescopes, would have been successful in gazing on and keep pace with the travelling rock.