One of the most high-risk asteroids that could hit Earth will not pose a serious threat to the planet for at least the next 100 years, US space agency Nasa has said.
The near-Earth object was at risk of hitting the planet in 2068, but new observations by astronomers have confirmed the planet is safe for another century.
Apophis was discovered in 2004 and is expected to make an extremely close approach to Earth in 2029, flying 32,000 kilometres above the planet’s surface.
It measures 340 metres in diameter, equivalent to about seven Olympic-sized swimming pools and taller than the Empire State Building in New York.
“A 2068 impact is not in the realm of possibility anymore, and our calculations don’t show any impact risk for at least the next 100 years,” said David Farnocchia, an official at Nasa’s Centre for Near-Earth Object Studies.
"With the support of recent optical observations and additional radar observations, the uncertainty in Apophis' orbit has collapsed from hundreds of kilometres to only a handful of kilometres when projected to 2029.
“This greatly improved knowledge of its position in 2029 provides more certainty of its future motion, so we can now remove Apophis from the risk list.”
The space rock made a safe flyby about three weeks ago, when it flew 16.4 million kilometres above Earth's surface.
It was then that astronomers used powerful radar observations to produce newer estimates of Apophis' orbit around the Sun, helping rule out any impact risk in 2068.
“When I started working with asteroids after college, Apophis was the poster child for hazardous asteroids,” Mr Farnocchia said.
“There’s a certain sense of satisfaction to see it removed from the risk list, and we’re looking forward to the science we might uncover during its close approach in 2029.”
The asteroid will be visible to the naked eye in 2029 to observers in the Eastern Hemisphere.
It will also be an extremely rare opportunity for astronomers to get a close-up view of a space rock.
What does Apophis mean?
In Egyptian mythology, Apophis was a serpent and enemy of the Sun God, called Ra. Apophis wanted to bring eternal darkness on the world before being defeated by Ra.
Therefore, the asteroid has been dubbed as the ‘God of Chaos’.
The space rock’s full name is Apophis 99942 and was given a 2.7 per cent chance of hitting Earth in 2029 when it was first discovered 17 years ago.
What happens if it hits Earth?
Apophis could cause destruction of up to several hundred kilometres from its impact site, according to the Planetary Society. It would release the energy equivalent of almost 800 megatonnes of TNT, tens of thousands times more powerful than the bomb dropped on Hiroshima.
The asteroid that led to the extinction of dinosaurs, however, was much larger than Apophis.
Is the 2029 close approach dangerous?
The next close approach to Earth is not going to impact the planet, but it will fly extremely close.
It will be visible to people in the Eastern Hemisphere without the aid of telescopes or binoculars.