On Friday, an asteroid half the size of a football field passed closer to the Earth than any other known object of its size has in the past, on the same day an unrelated and much smaller space rock blazed over central Russia, creating shock waves that shattered windows and injured around 1,200 people.
Asteroid 2012 DA14, discovered just last year, passed about 27,700 kilometers from the Earth at 7:25 pm GMT, closer than the networks of television and weather satellites that ring the planet.
"It's like a shooting gallery here. We have two rare events of near-Earth objects approaching the Earth on the same day," NASA scientist Paul Chodas said during a webcast showing live images of the asteroid from a telescope in Australia.
Scientists said the two events, though both rare, are not related. The body that exploded over Chelyabinsk, Russia at 3:20 am GMT Friday came from a different direction and different speed than DA14.
Astronomer Donald Yeomans, with NASA's Jet Propulsion Laboratory in Pasadena, California, said rocks the size of basketballs enter the atmosphere every day. Things the size of a small car arrive every couple of weeks. Larger meteors are less common, so the frequency of occurrences decreases, he added.
The Russian fireball was the largest space rock to hit Earth's atmosphere since the 1908 Tunguska event when an asteroid or comet exploded over Siberia, leveling 80 million trees over 2,150 square kilometers, NASA said.
Asteroid DA14 blazed past the planet at about 13 kilometers per second. At that speed, an object of similar size on a collision course with the Earth would strike with the force of about 2.4 million tons of dynamite, the equivalent of hundreds of Hiroshima-type bombs.
Meanwhile, some residents in Cuba's central province of Cienfuegos said they saw an object fall from the sky at around 1 am GMT Friday which turned into a fireball "bigger than the sun" before it exploded, a Cuban TV channel reported.
Cuban experts have been dispatched to the area to look for possible remains of the meteor-like object, said the report. It remains unknown whether the reported phenomenon in Cuba is related to Friday's meteor strike in central Russia.