[Watch] Asteroid in rare earth fly-by

Astronomers around the world aimed their telescopes to catch a glimpse of the 2005 YU55 asteroid, which is about as big as an aircraft carrier but was not visible to the naked eye when it passed by at its closest point at 2328 GMT.

"Frankly, for anybody this is going to be really hard to see. This is 100 times more dim than what the human eye can see. You need a good telescope," NASA spokeswoman Veronica McGregor said before the fly-by.

The near-spherical, 1,300-feet (400-metre) in diameter asteroid often travels in the vicinity of earth, Mars and Venus, but "the 2011 encounter with Earth is the closest this space rock has come for at least the last 200 years," the US space agency said.

Other asteroids of this size pass by Earth frequently, though the last such event happened in 1976 and the next will not happen again until 2028, when an asteroid called 2001 WN5 will skim about halfway between the Moon and Earth.

NASA said at the point of closest approach was yesterday, the 2005 YU55 asteroid "was no closer than 201,700 miles (324,600 kilometres), as measured from the center of Earth" -- roughly .85 times the distance of the Moon to the earth.