A 75-meter-wide asteroid will pass the Earth of Friday, the third of three 'potentially hazardous' rocks flying past out planet this week. Asteroids 2012 DK31, 2006 BE55, and 2021 QW are all being tracked by NASA as they pass 'close' to Earth.
The first one started moving past us on Monday. It measured about 137 metres in diameter, and is thought to be as wide as the height of a 40-floor skyscraper. The second one started coming close to Earth last night, and is the closest of the three.
That one flies by every four or five years.
