Asteroid 1999 KW4, which is 1.5 kilometres long, is so big that it will bring with it its own Moon – which is half a kilometre wide – and it has been classed as a “potentially hazardous asteroid”. The asteroid will pass at a distance of 3 million miles away, which is classed by NASA as a near-Earth object. The giant space rock will zoom past Earth on Saturday, May 25, at 7.05PM ET – or 12.05AM (GMT) on Sunday.
NASA said on its website: “This object will be the target of an extensive observing campaign supported by NASA’s Planetary Defense Coordination Office.
“1999 KW4 has been classified as a ‘Potentially Hazardous Asteroid’ by the Minor Planet Center.”
The European Space Agency (ESA) said in a statement: “The goal is to put observatories and telescopes to the test, to become aware of what kind of information can be collected on short notice in case of a future close approach of a possibly threatening asteroid.”
Asteroid 1999 KW4 is part of a binary system – much like the Earth and the Moon are – and scientists state it is one of the closest flybys of its time.
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Vishnu Reddy, a planetary scientist at the University of Arizona in Tucson, said: “It’s one of the closest binary flybys probably in recent history.
“That’s what makes it a very interesting target.”
Although classified by NASA as technically “potentially hazardous”, asteroid 1999 KW4 will breeze by safely.
Even at its closest, the space rock fly-by 3,216,271 miles from Earth – 13.5 times the distance to the moon.
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Asteroid 1999 KW4 was discovered on May 20, 1999 by the LINEAR collaboration using the Goldstone and Arecibo observatories.
The asteroid orbits the sun roughly approximately every 186 days on an elliptical path.
The space rock has has made a succession of near Earth Earth approaches in the last century, and will get even closer with its next approach in May 2036.