NASA says asteroid four times as big as the Shard is days away from Earth fly-by

A colossal asteroid is expected to shoot past Earth in just days, according to reports from NASA.

Astronomers believe that the rock, known as 138971 (2001 CB21), is potentially hazardous and measures between 1,840 and 3,940ft in diameter.

The space rock will zoom past Earth at almost 26,890 miles per hour, according to their calculations.