A recently discovered asteroid nicknamed The Beast is expected to make its closest approach to Earth this Sunday.

The asteroid goes by the official name 2014 HQ124 and was discovered April 23 by NASA's Wide-field Infrared Survey Explorer (WISE) space telescope.

Astronomers said it's not considered a threat to collide with the planet.

The flyby will see it pass by at a range of 3.25 times the distance between the Earth and moon.

This will be the closest approach an object of this size has made since 2005 YU55 in November 2011. YU55 whizzed past Earth closer than the moon's orbit to our planet.

The online Slooh community observatory in Chile captured the asteroid for viewers on Thursday. The asteroid has been out of reach of all but most southern telescopes.

The asteroid is considered large for a near-Earth object, with a diameter of 325 metres, according to Slooh.

HQ124 is at least 10 times bigger, and possibly 20 times, than the meteor that exploded over Chelyabinsk, Siberia, last year and injured more than 1,100 people, Slooh astronomer Bob Berman said.

Berman said that object was "maybe the size of a movie theatre," while NASA compared its size to a bus.

"[HQ124] is a fifth of a mile," Berman said in a webcast Thursday.

"It's not a super-large one. You call it The Beast, but there are much bigger ones," American physicist Mark Boslough, an expert on planetary impacts, told Slooh.com during the webcast. "We've discovered most of the ones greater than a kilometre."

Still, Boslough said that a planetary strike with an object the size of HQ124 would have a catastrophic effect.

"It's moving at a relative speed of 14 kilometres per second. But if it were headed toward us, gravity would speed it up and it would hit the Earth with a speed of 18 kilometres a second," he said.

Based on its size, and assuming it would still be a solid rock at the time of impact, it would lead to an explosion of about 2,000 megatonnes, enough to wipe out an entire metropolitan area," Boslough said.