Asteroid passing near Earth on Friday

An asteroid between 50 and 130 feet wide will fly by the Earth on Friday on a path closer than the moon's, NASA said this week.

Asteroid 2018 CB is the second small asteroid to buzz by the planet this week, according to NASA.

"Asteroids of this size do not often approach this close to our planet -- maybe only once or twice a year," said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California.

The newly discovered space rock will pass within 64,000 kilometres of Earth on Friday afternoon. That's less than one-fifth the distance to the moon.

The manager of NASA's Center for Near-Earth Object Studies, Paul Chodas, said asteroids this size usually don't come this close -- just once or twice a year.

While Friday's close approach isn't a huge deal, Chodas said in an email, "it is a reminder that asteroids can pass very close to our planet and it's important that we find these objects when they do get close."

It will be the second time this week an asteroid buzzes us. On Tuesday, an asteroid passed within 184,000 kilometres, slightly more than halfway to the moon.

Both of this week's asteroids were discovered Feb. 4 by astronomers at the NASA-funded Catalina Sky Survey in Arizona. Last year, more than 2,000 previously unknown near-Earth asteroids were discovered, according to Chodas.

A whopper asteroid named Apophis -- estimated at approximately 1,000 feet or more than 300 metres -- will pass at just one-tenth the distance between Earth and the moon in 2029. In the meantime, astronomers are on the lookout for asteroids lurking in the cosmic shadows.

"These asteroids are simply too small to be detected until they get really close to our planet," he wrote.

That was the case at Chelyabinsk, Russia on Feb. 15, 2013; the incoming object -- an intense fireball as it entered the atmosphere -- caught everyone by surprise.