NASA asteroid WARNING: Asteroid SL16 to zip past Earth in FIVE HOURS

The barrelling space rock, dubbed Asteroid SL16 by , is on track to skim past the planet shortly after 10pm UK time.

NASA expects the asteroid to make a so-called Earth Close Approach tonight at 10.09pm BST (9.09pm UTC), with a margin of error of less than one minute.

Based on NASA’s surveys, Asteroid SL16 could measure up to about half the height of Westminster’s famous Elizabeth Tower – home to Big Ben.

NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, estimates the asteroid is somewhere between 59.05ft and 134.5ft (18m to 41m) in diameter.

Big Ben’s clock tower in comparison stands tall over London’s Westminster at a height of 314.96ft (96m).

This also means the could be between the size of one to four London double-decker buses stacked in a row.

But the asteroid’s formidable size is not its only terrifying feature – the asteroid is also incredibly fast.

According to NASA’s JPL, the space rock covers more than six kilometres of space every single second – an incredible speed of 14,361.13mph.

The asteroid is many times quicker than the fastest passenger aircraft ever built, the Concorde.

The supersonic airliner could reach top speeds of up to 1,354mph (2,179km/h).

But just how close will the speedy asteroid approach the planet tonight?

Despite making a so-called Earth Close Approach, the asteroid will appear to be incredibly far from our home world – in human terms at least.

At 10.09pm BST (9.09pmUT) the space rock will reach a nominal close approach distance of 0.02183 astronomical units (au) or 8.29 lunar distances.

A single au is a value used by astronomers to measure distances in space and is the distance between the Earth and the Sun.

One lunar distance is the average amount of space between the Earth and the Moon.

This means NASA’s astronomers expect Asteroid SL16 to approach Earth from no closer than 2.02 million miles (3.26 million km).

Asteroid SL16 is a so-called Near-Earth Object (NEO), which means it will pass the Earth from a distance smaller than 1.3au or more than 92.95 million miles (149.59 million km).

NASA explained: “Near-Earth Objects are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth’s neighbourhood.

“Composed mostly of water ice with embedded dust particles, comets originally formed in the cold outer planetary system while most of the rocky asteroids formed in the warmer inner solar system between the orbits of Mars and Jupiter.”

The distances reached by NEOs might seem incredibly vast but on a cosmic scale they are incredibly close brushes.

As of June 2013, there are more than 10,000 know Near-Earth Asteroids (NEAs) and NASA pays close attention to them.

According to the agency, about 1,409 are classified as Potentially Hazardous Asteroids (PHAs) and could pose a threat to the planet.

Occasionally these asteroids cross path with the Earth’s orbit and these space rocks are known as Earth crossers.

Alongside tracking NEOs for the purpose of protecting the Earth, NASA aims to study these space rocks to learn more about the early solar system.